developing pedagogical tools to improve teaching multiple
TRANSCRIPT
Developing Pedagogical Tools to Improve Teaching Multiple Models of the Gene in High School
By
Nantaya Auckaraaree
A dissertation submitted in partial fulfillment of
the requirements of the degree of
Doctor of Philosophy
(Curriculum and Instruction)
at the
UNIVERSITY OF WISCONSIN-MADISON
2013
Date of final oral examination: 12/05/13
The dissertation is approved by the following members of the Final Oral Committee:
Noah W. Feinstein, Assistant Professor, Curriculum and Instruction John L. Rudolph, Professor, Curriculum and Instruction Melissa L. Braaten, Assistant Professor, Curriculum and Instruction Erica R. Halverson, Associate Professor, Curriculum and Instruction David L. Nelson, Professor Emeritus, Biochemistry
© Copyright by Nantaya Auckaraaree 2013
All Rights Reserved
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Abstract
Multiple models of the gene are used to explore genetic phenomena in scientific practices and in
the classroom. In genetics curricula, the classical and molecular models are presented in
disconnected domains. Research demonstrates that, without explicit connections, students have
difficulty developing an understanding of the gene that spans multiple domains, as is necessary
to solve authentic genetics problems. This dissertation describes the development and testing of
pedagogical tools for teaching multiple gene models with the goal of coherent, integrated, and
meaningful understanding. A design-based research study was conducted in collaboration with
secondary school teachers in Thailand. Prior to using the tools, most teachers applied the two
models separately to different domains, either relying on their default (preferred) model, or
making a partial connection between models. A few teachers meaningfully integrated the
models, demonstrating complex conceptual linkages and tailoring their use of models to the
context. Participating in the development and implementation of the tools helped teachers deepen
their own understanding of multiple gene models. Furthermore, results demonstrate that the tools
helped high school students achieve an integrated knowledge of both models and appropriately
apply the models in problem-solving contexts. The study identifies three principles for designing
learning materials: engaging with multiple linked representations, applying multiple models in
context, and connecting ideas about gene, protein, and phenotype around a circle of
representations. Findings from this study could also improve our understanding of the role
representations play in bridging different models, and of knowledge structure in other topics
involving multiple models.
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Acknowledgements
First and foremost, I would like to sincerely express appreciation and gratitude to my
advisor, Professor Noah Feinstein, for his excellent guidance, constructive discussions, and great
support. It has been an honor to be his first Ph.D. student. I appreciate all his contributions of
theoretical insights, vision, and time. He has patiently provided advice and encouragement for
me to productively proceed through the doctoral program and complete the dissertation. Without
his guidance, this dissertation would not have been possible.
My dissertation committee has been tremendously helpful through this process. I would
like to thank Professor John Rudolph and Professor Melissa Braaten for guiding my research and
writing, and for providing constructive criticism regarding scientific models, pedagogical tools,
and student learning. I am also grateful to Professor Erica Halverson for helping me develop a
stronger background in qualitative research, and ideas on scientific representations. Professor
David Nelson influenced me greatly as well, as he provided valuable perspectives on genetics
education and guidance on designing the materials.
I would like to acknowledge the Institution for Promoting Science Teaching and
Technology in Thailand that provides me the necessary financial support for pursing my Ph.D.
Thanks to the Milton O. Pella Graduate Fellowship, I could successfully conduct the
international study. I also would like to extend my sincere thanks for the participating schools,
teachers, and students, for their willingness and co-operation to participate in this study.
It has been a wonderful experience to be a part of UW-Madison graduate school. Thanks
to the faculty members in the Department of Curriculum and Instruction who have sharpened my
thoughts on science education. Particularly, I am grateful to Professor James Stewart, my
master’s degree advisor, who help me developed the initial ideas of this study. I also would like
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to thank my fellow graduate students in Science Education who provided helpful suggestions
about this project. I would especially like to thank my graduate colleague, Sarah Adumat, for her
kind assistance and valuable comments on my writing.
Special thanks to my friend in Thailand, Thanit Uerkanarak for encouragement, supports,
and suggestions particularly on data presentation. Thanks to my cousin, Nontapot, for assistance
in transportation during the data collection in Rawai city.
Most importantly, I wish to express my love and gratitude to my beloved family for
always being supportive throughout my study. I warmly appreciate my sisters Utisa and Dr.
Kanya for their supports and encouragement. I wholeheartedly dedicate this dissertation to my
father, Vorapot, who strongly advised me to pursue a Ph.D. degree abroad, and to my mother,
Jongkonnee, whom I cherish for always giving me invaluable inspiration. I owe them my
heartfelt appreciation.
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Table of Contents
Abstract ............................................................................................................................................ i
Acknowledgements ......................................................................................................................... ii
Table of Contents ........................................................................................................................... iv
List of Tables ............................................................................................................................... viii
List of Figures ................................................................................................................................ ix
CHAPTER 1: Introduction ............................................................................................................. 1
Structure of the Dissertation ....................................................................................................... 1
Part I: Introduction to the Research ................................................................................................ 2
A Rationale for the Study ........................................................................................................... 2
Research Questions ..................................................................................................................... 6
Significant of the Study .............................................................................................................. 7
Part II: Theoretical Frameworks ..................................................................................................... 8
How Student Learn Science ........................................................................................................ 8
Scientific Models ...................................................................................................................... 11
Multiple Representations .......................................................................................................... 16
Teachers’ Knowledge ............................................................................................................... 18
Conceptual Framework ............................................................................................................. 23
Part III: Science Education in Thailand ........................................................................................ 25
Thailand’s Education System ................................................................................................... 25
v
Learners’ quality at basic education level ..................................................................................... 27
High School Genetics ............................................................................................................... 28
Issues of Science Education in Thailand .................................................................................. 30
CHAPTER 2: Literature Review .................................................................................................. 35
Introduction to the Chapter ....................................................................................................... 35
Students’ Understanding of the Gene Concept ......................................................................... 38
The Gene Concept as Multiple Scientific Models .................................................................... 47
Multiple Models of the Gene .................................................................................................... 50
The Analysis of the Gene Concept in the Science Curriculum ................................................ 59
Discussion ................................................................................................................................. 68
CHAPTER 3: Methodology .......................................................................................................... 71
Introduction to the Chapter ....................................................................................................... 71
Research Design ........................................................................................................................ 72
Recruitment and Sample ........................................................................................................... 78
Data Collection ......................................................................................................................... 84
Data Analysis ............................................................................................................................ 92
CHAPTER 4: Exploring Teachers’ Knowledge about Multiple Models of the Gene .................. 97
Introduction to the Chapter ....................................................................................................... 97
Teachers’ Conceptions of the Gene .......................................................................................... 98
Teachers’ Use of Multiple Models of the Gene ...................................................................... 104
vi
Cross-Case Analysis of Teachers’ Conceptions of Multiple Models of Genes ...................... 126
Teachers’ Pedagogical Content Knowledge ........................................................................... 129
CHAPTER 5: Finding Pedagogical Tools to Improve Teaching Multiple Models of the Gene 135
Introduction to the Chapter ..................................................................................................... 135
Part I: Developing Pedagogical Tools to Improve Teaching the Gene Concept ........................ 136
The Principles underpinning the Designed Learning Materials ............................................. 137
The Designed Learning Materials ........................................................................................... 142
Redesigning the Designed Learning Materials ....................................................................... 145
Part II: Implementation of the Designed Learning Materials in Thai Classroom....................... 146
Classroom Implementation ..................................................................................................... 146
Teachers’ Opinions on Implementing the Learning Materials in Thai Classrooms ............... 152
Part III: The Impact of the Designed Learning Materials on Students’ Understanding of Multiple
Models of the Gene ..................................................................................................................... 161
Students’ Conceptions of the Gene ......................................................................................... 162
Students’ Use of Multiple Models of Genes ........................................................................... 169
Cross-case analysis between default model and application. ................................................. 186
CHAPTER 6: Discussions and Conclusions............................................................................... 191
Key Findings ........................................................................................................................... 191
Limitations of the Study.......................................................................................................... 200
Implications for Practice and Research ................................................................................... 201
vii
References ................................................................................................................................... 204
Appendix A: Research Instruments ............................................................................................ 219
Appendix B: Designed Learning Materials ................................................................................ 231
viii
List of Tables
Table 1 Features of Cognitive Approach ........................................................................................ 9
Table 2 Indicators Relating to Genetics from Secondary School Science Curriculum. ............... 29
Table 3 Examples of Students’ Responses and Students’ Conceptions of Genes Categories ....... 45
Table 4 Examples of Students’ Response about the Meaning and Function of Genes. ................ 46
Table 5 Description of Different Characteristics of Gene Models. .............................................. 55
Table 6 Examples of Representations Depicting the Classical Gene Model, the Molecular Gene
Model and Phenotype. .................................................................................................................. 60
Table 7 Teacher Participant Information ..................................................................................... 80
Table 8 Student Participant Information ...................................................................................... 82
Table 9 School Information .......................................................................................................... 84
Table 10 Triangulation Matrix for Research Questions with Multiple Data Collection Methods 85
Table 11 The Guiding Questions for Approaching the Data ........................................................ 93
Table 12 Teachers’ Descriptions of the Gene and the Function of the Gene ............................. 100
Table 13 Teachers’ Drawings of the Gene ................................................................................. 102
Table 14 Examples of Students’ Descriptions of the Gene and the Function of the Gene ......... 163
Table 15 Students’ Drawings of the Gene ................................................................................. 168
Table 16 A Summary of Students’ Conceptions and Connections of Multiple Models of the Gene
across Cases................................................................................................................................ 190
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List of Figures
Figure 1. Conceptual framework of the study. ............................................................................. 24
Figure 2. Structure of the education system in Thailand .............................................................. 26
Figure 3. Relationship in the development of learners’ quality according to the Basic Education
Core Curriculum ........................................................................................................................... 27
Figure 4. A pathway indicating the students’ progress through progressively more sophisticated
mental models of gene .................................................................................................................. 42
Figure 5. The framework of the relationships among mental models, conceptual models, and
physical world ............................................................................................................................... 48
Figure 6. Research design and data collection in three phases ..................................................... 74
Figure 7. Examples of descriptions and drawings of the gene ................................................... 104
Figure 8. Representations of genes in the interview task for eliciting connection between the
models. ........................................................................................................................................ 105
Figure 9. Partial connection between classical and molecular models. ..................................... 110
Figure 10. Teera’s multiple representations of gene. ................................................................. 112
Figure 11. Uma’s drawing of a gene. ......................................................................................... 116
Figure 12. Cross-Case Analysis of Teachers’ Conception of Multiple Models of Genes. ........ 127
Figure 13. The representations in Activity 1 that students are asked to connect. ...................... 143
Figure 14. Examples of representations and a scenario in Activity 2 ........................................ 143
Figure 15. Examples of representations shown in Activity 3 ..................................................... 144
Figure 16. Examples of proteins’ structures created by the students ......................................... 145
Figure 17. Cross-Case Analysis of Students’ Conceptions of Multiple Models of the Gene. ... 187
Figure 18. The cycle of representations in genetics ................................................................... 199
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CHAPTER 1: Introduction
This dissertation presents a design-based research project that explores the challenges of
learning and teaching multiple models of the gene at the high school level. It seeks to advance
pedagogical theory useful for developing integrated knowledge and meaningful applications of
multiple models of the gene. In my efforts to bridge educational theory and classroom practice, I
conducted multiple iterations of data collection with biology teachers and high school students in
Thailand. This paper presents a theoretical argument of how the disconnected gene concept in
the high school curriculum hinders a complete understanding of genetics among students; it also
discusses how teachers and students construct connections across multiple gene models to
explain genetics problems across domains. This study will then describe pedagogical tools based
on multiple linked representations to promote a more integrated knowledge of the gene concept.
Finally, the study will end with a discussion of any implications the finding might have on
classroom instructions.
Structure of the Dissertation
Chapter 1 provides an overview of this dissertation study. The first section, an
Introduction to the Research, presents an overview of the problem, a rationale for the study,
research questions, and purposes of the study. The second section discusses the theoretical
framework on which my research is based, and establishes the general context of science
education in Thailand. Chapter 2 provides deeper conceptual background, outlining how the
current depictions of “what a gene is” in the high school science curricula can be connected to
the challenges students experience in learning genetics. This chapter also situates the study
within the broader research on genetics education and the use of multiple linked representations.
Chapter 3 details my methodological approach, recruitment and sample, data collection, and data
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analysis. Chapter 4 focuses on the teachers in my study, describing the structure of their
knowledge and their pedagogical content knowledge regarding multiple models of the gene.
Chapter 5 focuses on the students in my study, first reviewing the development of the designed
learning tools, and then presenting the results of those tools being implemented in Thai
classrooms, particularly on students’ learning of genetics. The final chapter summarizes the
findings based on the previous chapters, discusses developed pedagogical tools, and outlines the
implications and limitations of the study.
Part I: Introduction to the Research
A Rationale for the Study
The field of genetics has been progressing rapidly, and most of its recent development,
including both research and application, has focused on molecular genetics. Taking into account
the overarching educational goal of preparing scientifically literate learners, it is worth asking
whether students are prepared to make sense of this rapidly changing field and which approaches
teachers might use to teach this complex topic. Condit (2010) claimed that “the public
understand genetics through the lens of heredity, not in terms of the structural and functional
nature of genes” (p. 1). In other words, the public’s understanding of genetics is based on the
idea that traits are transmitted in families, and may not include the idea that genes, along with
environmental factors, act to control functions and structures of the body.
To make sense of contemporary genetics, students need background knowledge of the
molecular gene, which envisions genes as sequences of instructions inherited from parents to
control structures and functions of organisms. However, studying genetics also entails reasoning
through abstract ideas, complex mechanisms, invisible phenomena, and multiple biological
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organization levels (Duncan, 2007; Finley, Stewart, & Yarroch, 1982; Kindfield, 1992;
Malacinski & Zell, 1995; Stewart & Van Kirk, 1990; Wynne, Stewart, & Passmore, 2001).
Several research studies, based on the conceptual change theory of learning, revealed that
few students conceptualized genes as sequences of instructions (e.g. Duncan & Reiser, 2007;
Tsui & Treagust, 2007; Venville, Gribble, & Donovan, 2005; Venville & Treagust, 1998). In my
master’s thesis (2009), the results from a survey with 97 Thai high school students confirmed
that after instruction in genetics a majority of students viewed genes as active particles (an idea I
will discuss further below), while only ten students viewed genes as sequences of instructions.
Furthermore, interviews with a sub-sample of six students indicated that students’ conception of
genes influenced their explanations of genetic phenomena. Past research findings also
demonstrate that students need to understand genes, proteins, genetic information, cell, and traits
in integration in order to fully understand gene expressions (Duncan & Reiser, 2007; Duncan,
2007; Friedrichsen & Stone, 2004). Incomplete and partial understanding of genes and proteins
has been documented across ages ranging from middle school to college students and in various
national contexts such as United States, Australia, Germany, and Thailand (Auckaraaree, 2009;
Duncan & Reiser, 2007; Freidenreich, Duncan, & Shea, 2011; Lewis & Kattmann, 2004;
Venville & Treagust, 1998).
The previous studies provide a decent starting point for an analysis of student
understanding. However, since these studies were largely based on conceptual change theory, it
is problematic to only rely on this framework to interpret students’ understanding of genes. The
previous studies concluded that students who did not view genes as sequences of instruction
developed an understanding that were “intelligible, partly plausible but not fruitful” (Tsui &
Treagust, 2004; Venville & Treagust, 1998). However, a relationship between these two
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conceptions of the gene is not that one is ‘an alternative conception’ needed to be challenged and
changed to ‘a scientific conception’, as a premise of the theory. Tsui and Treagust (2004)
contended that, learning genetics should allow both conceptions of genes “to coexist and to
access both meanings depending on context” (p. 200). Therefore, an understanding of the gene
concept is a complementary combination of these two conceptions of the gene—both as particles
and information.
Other researchers analyzed textbooks and curricula through the lens of a scientific model
approach (Flodin, 2009; Gericke & Hagberg, 2006, 2009, 2010; Stewart, Cartier, & Passmore,
2005). Scientists use scientific models that are tentative schemes or structures corresponding to
complex phenomena in nature to make abstraction visible and to provide the basis for
explanations and predictions about scientific phenomena (Gilbert, 2005; NRC, 1996; Passmore
& Stewart, 2002). In genetics, multiple scientific models of the gene have been used to explain
genetic phenomena, and each model has been developed to serve particular functions (Portin,
2002). Gericke & Hagberg (2006, 2009, 2010) indicated that textbooks portray different models
of genes separately in sub-disciplines or contexts. In order to understand students’ learning
experience with the genes, we should recognize that there are at least two scientific models of the
gene—each of which is useful in the proper contexts. The two particular models are the classical
model representing the gene as a particle, and the molecular model representing the gene as a
sequence of instructions.
To understand genetics, students must be able to integrate their knowledge of both
models and apply them each in appropriate contexts. As Stewart et al. (2005) pointed out genetic
literacy is attained by understanding the interrelated models of genes: not only understanding the
separate models, but also be able to integrate them to generate coherent and comprehensive
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explanations of genetic phenomena. Without an understanding of how genes bring about
phenotypes, students are essentially missing the molecular model (Stewart et al., 2005), and it
becomes a challenge for students to apply the appropriate models in particular contexts (Gilbert
& Osborne, 1980).
My argument is that current teaching provides few bridges for students to make
connections between classical and molecular genetics; in other words, the molecular gene model
is not presented during classical genetics or vice versa. We simply assume that students will be
able to build a bridge between those models and apply them fruitfully. Current genetic
curriculum leaves pieces of the two models unconnected, which affects student understanding of
the genetic phenomena. Educational research has shown that students learn better by connecting
concepts to coherently build a big idea. Duncan & Reiser (2007), for example, suggested that
students need “the link” between an information level (genetic information, sequences of
nucleotides) and a physical level (genetic material, chromosome, DNA, etc).
Yet, very little work has attempted to situate knowledge about multiple models in the
context of classroom practices. Other researchers who have attempted to design learning
materials for teaching genetics have only investigated genetic knowledge in a particular domain,
instead of across several genetics domains. For instances, Passmore & Stewart (2002) and Tsui
& Treagust (2004) attempted to connect the classical model to meiosis processes while solving
the classical genetics problems. Duncan & Tseng (2011), on the other hand, emphasized the
importance of students’ mastering of the role of proteins and genes to learn molecular genetics.
To advocate for an integrated knowledge of multileveled genetic phenomena, there is a need for
research that explores pedagogical tools that facilitate students’ ability to link multiple models of
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the gene, and to apply the appropriate models across both classical and molecular genetics
domains.
The present study focuses on the underlying question: How should teachers navigate
multiple scientific models of the gene to promote a more comprehensive understanding of the
gene? The learning materials that I developed in collaboration with the teachers aim to foster
exactly that, coupled with students’ awareness of the relationship between the two models, and
their application of both models to explain genetic phenomena in real world situations. While
research on curriculum design remains necessary, a more robust understanding of classroom
practices is equally important because the materials need to be tailored to classroom contexts.
Largely missing from much of the existing research are portrayals of teachers’ knowledge
with regards to multiple scientific models. An effective way to address this issue would be to
identify effective pedagogy for connecting multiple models of genes, which requires teachers to
utilize their science content knowledge and expertise in the classroom. In addition to proposed
design strategies based on educational theories alone, teachers’ emerging pedagogical content
knowledge and their structure of knowledge could also serve as guidelines for developing further
pedagogical theories on the multiple models of the gene.
My design-based research is situated within the Thai educational context, and will
highlight aspects unique to Thai classrooms. Because the challenge of learning about genes has
been observed in many countries, however, it is my hope that this research will also provide
findings of broader interests.
Research Questions
The literature review revealed the disconnections across multiple models of the gene in
high school genetics, which had led to a lack of comprehensive understanding of the gene among
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students. In the interest of teaching and learning different gene models, this design-based
research seeks to explore effective teaching practices for developing integrated knowledge and
meaningful applications of multiple models. To gain a clearer understanding of the context in
which these practices must be used, I investigated five aspects of teaching and learning about
genetics:
1. What are teachers’ content knowledge and pedagogical content knowledge about the
multiple models of the gene?
2. What are effective pedagogical strategies for teaching multiple models of the gene
with the goal of coherent, integrated, and meaningful understanding?
3. How do the learning materials created in this design-based research project impact
student understanding of multiple models of the gene?
4. What are the factors that influence the implementation of the designed learning
materials in Thai classrooms?
The first research question examined teachers’ knowledge necessary for designing the
tools and informing professional development. The second question on instructional guidelines is
the main objective of this study. The goal is to facilitate students’ transition to a more coherent
view of the gene that incorporates both models, and to enable them to use the appropriate model
to explain genetic phenomena meaningfully in different contexts. The last two questions focus on
students’ learning and the pragmatic aspects of practice, which will in turn be used to monitor
the outcomes of the modified tools.
Significant of the Study
The results from this study will serve the greater educational community by attempting to
improve genetic instructions and secondary science teacher education, specifically in regard to
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the teaching of multiple scientific models. This research will potentially develop promising
instructional approaches for more effective high school genetics curriculum. Findings from this
research will also contribute to biology curriculum development, professional development for
science teachers, and, through those mechanisms, to student learning. Moreover, this study will
bridge the gap between educational research and practice by researching in an authentic context.
Part II: Theoretical Frameworks
A basic principle in designing instructional materials is developing an understanding of
desired outcomes and the learners’ knowledge and skills, according to backward design
(Wiggins & McTighe, 2005). This study drew on literature about cognitive learning theory,
scientific modeling, and representation, to understand how science knowledge is constructed and
what students’ knowledge in genetics is desired. In addition, since teachers are seen as key
agents for accomplishing the reform-oriented goals of science teaching, this study also drew on
literature about teachers’ pedagogical content knowledge to inform the analysis of teaching
practices. The following subsections will briefly elaborate theoretical contributions from each
literature domain, while the last subsection will integrate the domains into the conceptual
framework used for this study.
How Student Learn Science
Following a review of literature on how students learn science, my study is based on the
assumption that students require both conceptual understanding and strategic knowledge to have
a fruitful understanding of genetics; a desirable learning outcome and an expertise in explaining
genetics with multiple models would involve their abilities to connect and organize information
about these models and to flexibly retrieve, and apply them in different contexts.
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Cognitive perspective. The review of learning theory in this section will form the basis
for discussions in the next section on how students make sense of scientific models. Cognitive
perspective on learning focuses on information processing and knowledge representation within
the learner (see Table 1). In other words, according to this theory, learning involves the
construction of meaning from an interaction between learners’ experiences and a new
understanding inside learners’ mind. According to Collins, Greeno, and Resnick (1996), the
cognitive approach “treats knowing as having structures of information and processes that
recognize and construct patterns of symbols in order to understand concepts and exhibit general
abilities, such as reasoning, solving problems, and using and understanding language” (p. 18).
Another camp based on situative perspective has shifted focus from individual learners to the
interaction of social and cultural factors (Brown, Collins, & Duguid, 1989; Lave & Wenger,
1991). This camp proposes that learners use tools that develop from a culture to mediate their
social environments and to serve social functions; the internalization of these tools in turn leads to
higher competence (Crawford, 1996). Cognitive and situative approaches shed light on different
aspects of the educational processes (Anderson, Greeno, Reder, & Simon, 2000; Sfard, 1998).
Table 1
Features of Cognitive Approach
Features Cognitive approach Focus on Individual development and Information processes Instructional goals Knowing the “what” Competence Acquisition of intellectual skills and its transference to new situations View on social processes
as communication and as a means for both motivating and stimulating thoughts
Curriculum design Information structures in conceptual understanding and procedures that are needed for students to succeed in the tasks
Ideas about representations
Cognitive research has shown that “learning to use specific representational forms can facilitate transfer between specific tasks” (Bassok & Holyoak, 1989; Novick & Hmelo, 1994).
Note. Adapted from Anderson, Greeno, Reder, and Simon (2000).
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In this study, I applied a cognitive approach to understand knowledge structure when
students solve genetics problems through the use of scientific models. Based on this approach,
the learning materials were developed to help students construct a conceptual understanding of
the gene by connecting information from different models. The emphasis of the study is on the
impact of the materials coordinated multiple representations on students’ cognitive and processes
to support scientific understanding.
Expert and novice knowledge. In cognitive psychology, there is a long tradition of
research that compares experts and novices to document similarities and differences in their
cognitive structures and processes (Bruner, 1960; Groot, 1965). This line of research provides
insights especially into problem solving and thinking. Expert-novice studies involve contrasts
between individuals at relatively high performance levels in a given domain (expert) and
individuals at relatively low performance levels (novice). According to NRC (2005), the key
principles of experts’ knowledge are:
• Experts notice features and meaningful patterns of information that are not noticed
by novices.
• Experts have acquired a great deal of content knowledge that is organized in ways
that reflect a deep understanding of their subject matter.
• Experts’ knowledge cannot be reduced to sets of isolated facts or propositions but,
instead, reflects contexts of applicability: that is, the knowledge is “conditionalized”
on a set of circumstances.
• Experts are able to flexibly retrieve important aspects of their knowledge with little
attentional effort.
• Experts have varying levels of flexibility in their approach to new situations (p. 32).
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Research on expertise argued for the importance of providing students with learning
experiences that specifically enhance their abilities to recognize meaningful patterns of
information and to apply it in all domains. Expert-novice studies point out the importance of
organized conceptual understanding and applying knowledge in contexts. This type of
understanding requires students to have both conceptual knowledge (knowing what) and
strategic knowledge (knowing when, where, and how our knowledge applies) in learning science
(Shavelson, Ruiz-Primo, & Wiley, 2005).
Scientific Models
What is a scientific model? Modeling and models are essential elements of scientific
practice that scientists use to develop an understanding of how the natural world works.
Scientists seek to provide explanations for complex natural phenomena to describe the causes
that lead to particular effects. Scientists use scientific models, which are tentative schemes or
structures that correspond to complex phenomena in nature, to make abstraction visible and to
provide the basis for explanations and predictions about scientific phenomena (Cartier &
Stewart, 2000; Gilbert, 2005; NRC, 1996).
The value of models and modeling to science education has increasingly been recognized
among the science education reform movements (AAAS, 1993; Giere, Bickle, & Mauldin, 1991;
NRC, 1996). However, there is no consensus among them regarding the definition of “model”.
The following brief review illustrates the wide range of definitions in the current science
education literature:
• A model is a simplified representation of a system, which calls for more attention on
specific aspects of the system (Ingham & Gilbert, 1991).
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• A model in science is a representation of a phenomenon initially produced for a
specific purpose (Gilbert & Boulter, 2000).
• A model is a representation of structure in a physical system and/or its properties
(Hestenes, 1997).
• Models are tentative schemes or structures that correspond to real objects, events, or
classes of events, and have explanatory power. Models help scientists and engineers
understand how things work (NRC, 1996).
• A model is a representation, usually visual but sometimes mathematical, used to aid
in the description or understanding of a scientific phenomenon, theory, empirical law,
physical entity, organism, or part of an organism (NSTA, 1995).
Halloun (2006) commented that most definitions describe models as a conceptual model,
a complex theoretical structure, but some researchers also use the concept to refer to physical
replicas of objects or systems (e.g. a globe) or representations (e.g. diagrams, equations, and
formulae) (e.g. Harrison & Treagust, 2000). This study uses the general definition put forth by
Passmore & Stewart (2002) that “a scientific model is an idea or set of ideas that explains what
causes a particular phenomenon in nature” (p. 188). According to Passmore & Stewart (2002),
representations are not models themselves. Representations of such scientific models are
essential tools for communicating about the models; however, the key aspect of models is to
function as tools for explaining or predicting natural phenomena. To illustrate, the authors
explained that while the meiotic model describes independent segregation of genes during
gamete formation with the function of predicting the possible allele combinations, the Punnett
square diagram is simply a representation of the selected aspects of the meiotic model.
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Abstraction to explanation. Gilbert (2005) pointed out that “models can function as a
bridge between scientific theory and the world-as-experienced (reality) in two ways” (p.11): (a)
by functioning as simplified depictions of a reality-as-observed for visualization purpose; and (b)
to be idealizations of a reality-as-imagined for prediction purpose. Gilbert also pointed out that
“models are also composed of abstractions, entities which are treated as if they are objects” (p.
11), this includes concept such as genes, energy, forces. The function of a model is therefore to
make abstraction visible for explanations, and to provide the basis for prediction of scientific
phenomena (Francoeur, 1997). Reasoning with models enables scientists to visualize the abstract
processes and entities they are investigating (Justi & Gilbert, 2002).
Limited power of explanation. The functions of models are to represent, explore,
explain, and predict complex phenomena. Models can portray objects, entities, processes, as well
as systems—and these could be at macro level or micro level (Gilbert, 2005). However, Halloun
(2006) cautions that a model, however, is a representation “of some things and for a specific
purpose” (p. 22); in other words, a constructed model focuses only on specific aspects of the
phenomenon in a set of questions, rather than demonstrates every aspect of the phenomena
(Ingham & Gilbert, 1991). Therefore, the explanation power of a model is limited. As Cartier,
Rudolph, & Stewart (2001) stated:
Once constructed, models influence and constrain the kinds of questions scientists ask
about the natural world and the types of evidence they seek in support of particular
arguments. They guide a researcher’s perception of what is involved in the natural
processes of the world. (p. 5)
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Socially constructed. Models are continuously assessed as they are used by a community
of scientists, based on their potential to explain data and to predict the results of observation, and
whether they are consistent with other ideas (Cartier, Rudolph, Stewart, 2001; Gilbert & Boulter,
2000). The complexity of models increases in order to probe new phenomena and collect
additional data (Gilbert, 2005). For instance, with the advance in knowledge about the chemical
structures of genetic materials, a molecular model was developed and scientists then became able
to explore other kinds of questions, such as the influence of environmental factor to gene
expression. Models that have gained acceptance in a community of scientists and play a central
role in conducting research in community are called consensus models (Gilbert & Boulter,
2000). Such models then play essential roles in the dissemination, communication, and
acceptance of that knowledge (Gilbert, 1991); consequently, models are both products of science
and cultural artifacts/tools of the scientific community.
Multiple models of one thing. Since the nature of a model is limited to depicting only
particular aspects of reality, multiple models of the same phenomenon could and should be
produced following different scientific developments. Multiple models could be different in
terms of functions, levels, or aspects in explaining particular phenomena; the difference,
however, is more complex than only merely differences in terms of the structures of their
respective representations. Halloun (2006) explained that multiple models are used to explain
complex phenomena like genetics and that those models cannot be replaced by another one:
Two scientific models may represent the same pattern without having one model
completely reducible into the other. However, the two models may not then belong to the
same scientific theory, and they cannot allow us look at the pattern from the same
perspective. (p. 43)
15
This quote nicely explains the nature of the multiple gene models. The classical gene
model and the molecular gene model are two scientific models that each holds different
explanatory and predictive powers. To fully appreciate and explain natural phenomena, students
must learn both of them. Learning Scientific Models. A model is socially constructed, used, and disseminated in
the scientific community, often by the means of representations. As a cultural artifact, a
simplified version of a historical or scientific model is often integrated into the curriculum and
classroom teaching (Gilbert & Boulter, 2000). Through discourse, students learn to explain
scientific phenomena and solve the problem with those scientific models as cognitive tools
(Driver, Asoko, Leach, Scott, & Mortimer, 1994). It is important to note that the use of a
representation (or a model) is not “an act of direct cultural transmission but a constructive
process during which the information that comes from the culture is interpreted and influenced
by what is already known” (Skopeliti & Vosniadou, 2007, p. 1). In other words, the teaching and
learning of models are not simply direct transference, but are in fact inventive processes.
The goal in learning a scientific model is not only to gain cognitive knowledge, but also
to apply that knowledge in proper contexts; this two fold task requires an ability to use
appropriate models as cultural tools of science to explain relevant scientific phenomena. Within
one science concept, there are often multiple scientific models based on its domains of
applicability. Therefore, “the challenge (of learning science in the classroom) lies in helping
learners to appropriate these models for themselves, to appreciate their domains of applicability
and, within such domains, to be able to use them” (Driver et al., 1994, p.7). Students acquire and
deploy these tools in particular situations and contexts usually led to higher competence.
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Multiple Representations
Scientists always use multiple representations in forms of drawings, graphs, equations,
three dimensional structures, or words to represent their ideas, and to communicate scientific
models. The drawings, replicas, or other representations are distinct from the underlying
conceptual models; however, models and representations are hard to separate in practice,
especially in science classrooms. In science classrooms, the use of representations often plays an
important role in enabling students to express their mental models and for teachers to impart
scientific knowledge. Since, many scientific phenomena are beyond the learners’ temporal,
perceptual, and experiential limits, teachers commonly use representations to make abstract
concepts more accessible to students (Kozma, 2000). As a result, the usage of multiple
representations in the classroom has been widely studied.
Kozma (2003) studied the use of multiple representations by experts (chemists) and
novices (students) by applying Johnstone’s framework (1993), in which models are expressed in
three distinct representational levels: (a) the macroscopic level, (b) the sub-microscopic level,
and (c) the symbolic level. Scientists sometime use multiple representations in a flexible and
implicit way: they may transit between the microscopic world, the macroscopic world, and
phenomena without being aware of it. Kozma (2003) found that, unlike experts, novices could
not move across or connect multiple representations with such fluency, so their understanding
and discourse are constrained by the features of individual representations. Indeed, one
characteristic of expertise is knowing what representations are appropriate for what tasks
(Kozma & Russell, 1997). As a result, Kozma suggested that students should be supported in
using “multiple-linked representations” to make explicit the connections among entities,
processes and phenomena:
17
The features of these multiple representations need to be linked, either by the
instructional environment or/and by the students. Linkages can be accomplished by any
of a variety of symbolic conventions that would allow students to map surface features of
one representation onto those of another. (p. 15)
In addition to Kozma, Ainsworth (1999) had also studied the functions of multiple
representations. According to Ainsworth (1999), multiple representations function to
complement (supporting complementary cognitive processes), constrain (using a familiar
representation to constrain the (mis)interpretation of a less familiar representation), and construct
(building a deeper understanding of a phenomenon through abstraction of, extension from, and
relations between the representations). In fact, a considerable amount of research has focused on
the effect of the use of multiple representations, especially with the use of computer programs
(e.g. Tsui & Treagust, 2003). While the use of multiple models and representations may not be problematic in the
context of communication within the scientific community, it may, however, easily lead to
confusion in the context of classroom learning. In learning about genes, students are challenged
with a transition and connection across multiple models in different domains. For secondary-
school students, the skills and conceptual demands of switching between representations and
phenomena can be overwhelming. If students could make sense of multiple representations of
genes and see explicit connections of representations between the two gene models, they may
also be able to make connections between models. For example, students interpret how a
representation of sequence of nucleotide correlates with a symbolic representation depicting
alleles and genotype.
18
Through engaging in authentic problems with the explicit use of models, students will
develop understanding of the topic by connecting models to phenomena (Harrison & Treagust,
1998). Learning and fully understanding new concepts requires multiple opportunities to use
those concepts in different contexts (NRC, 2005). Moreover, Cartier (1999) commented that
providing students opportunities to work with different models can support their inquiries and
understanding of these scientific models. Consequently, the designed learning materials in this
study have created a set of problems that require students to use multiple models of genes to
solve situated problems. This could reinforce the connections between gene models to genetic
phenomena, and strengthen students’ understanding about the respective functions of the models.
Teachers’ Knowledge
Traditionally in instructional reform, curriculum developers would provide a new plan of
instruction without taking into consideration teachers’ perspectives and expect teachers to
change their practice without any support. The lack of success of a project is often claimed to be
failure on the teachers’ part in adhering to the developers’ intention in the implementation
process. While this view is undoubtedly limiting and problematic, teachers do remain important
agents in reforming science leaning. Curriculum developers should collaborate with teachers in
the instructional development process and consider teachers’ knowledge and practice as essential
resources in reforming learning environments (Loucks-Horsley, Stiles, Mundry, Love, &
Hewson, 2009).
To accomplish exemplary teaching practice, a wide range of knowledge associated with
teaching is required, including conceptual understanding of the subject, pedagogical content
knowledge, beliefs about the nature of the subject, and actual teaching practices (Kennedy,
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1998). Science teachers integrate content and pedagogical knowledge in their pedagogical
knowledge frameworks (Sanders, Borko, & Lockard, 1993).
In particular, this study focuses on subject matter knowledge and pedagogical content
knowledge. The framework on teacher knowledge is used for two purposes: (a) to unpack the
content of teachers’ knowledge related to the teaching of genetics, and (b) to inform an effective
pedagogical approach for teaching multiple models.
Subject matter knowledge. Subject matter knowledge (SMK) refers to teachers’
conceptual understanding of science or their topic-specific knowledge. Certainly, teachers need
enough knowledge of a particular subject to recognize students’ misunderstanding and to justify
the importance of the main concepts and connections among main ideas. Based on Abell’s
review (2007) of the knowledge of science teaches, comparing to other science disciplines,
studies on teachers’ SMK in biology focus mostly on their knowledge in relation to subject
matter structures (e. g. Gess-Newsome & Lederman, 1993, 1995; Lederman, Gess-Newsome, &
Latz, 1994), and only a few studies emphasize teachers’ conceptions of specific concepts (e.g.
Greene, 1990). The review also showed that existing studies have illustrated a correlation
between SMK and teaching, namely that the level of teachers’ content knowledge had a
significant impact on how content was taught (e. g. Abell & Lederman, 2007; Gess-Newsome &
Lederman, 1995). When teachers demonstrated a lack of scientific understanding, there was a
limitation in their use of effective instructional strategies, planning, and activities to promote
conceptual understanding and scientific thinking among their students (Gess-Newsome &
Lederman, 1995).
Pedagogical content knowledge. Teachers possess content knowledge and seek to
transform it for students’ benefit using pedagogical content knowledge (Grossman, 1990).
20
Pedagogical Content Knowledge (PCK) is the amalgam of subject matter knowledge and
pedagogical knowledge, which is used in combination with other knowledge needed for teaching
in the classroom in order to make the content comprehendible to others (Shulman, 1986, 1987).
In other words, PCK is the knowledge about how to teach particular content in particular ways to
enhance student understanding. For instance, Shulman (1987) anticipated that one significant
aspect of PCK is for teachers to know multiple representations of ideas in a given topic, and
understand how they could effectively present those representations to students.
In addition, PCK also refers to specific topics knowledge, which is distinct from the
general knowledge of pedagogy (Van Driel, Jong, & Verloop, 2002). SMK is therefore
considered to be a prerequisite in developing effective PCK (De Jong, O. Van Driel, 2005; Gess-
Newsome & Lederman, 1995; Loughran, Berry, & Mulhall, 2006; Magnusson, Krajcik, &
Borko, 1999). Teachers need to have a rich conceptual understanding of the specific topics,
coupled with expertise in adapting teaching methods and strategies to specific contexts.
As a result, teachers’ knowledge, especially on teaching multiple models of genes, is
more complicated than a straightforward transformation of subject-matter knowledge into forms
accessible to the students. The idea that genetics curricula contain multiple models of genes
representing some facets of phenomena is possibly a new idea for many teachers, since teachers
may conceive science as one steady form of knowledge. Teachers must explore their pedagogies
to teach genetics in a new direction, which is different from what teachers traditionally believe
about science learning. In other words, unpacking their pedagogical content knowledge about the
topic would be more challenging for teachers than simply transferring what they know to
students.
21
In order to study teachers’ PCK about teaching gene models, my study will focus mainly
on two components of PCK, according to Magnusson et al.’s (1999) five components of PCK in
science teaching: (a) the knowledge of students’ understanding of science, and (b) knowledge of
instructional strategies. Since knowledge of science learners and knowledge of instructional
strategies is fundamental knowledge in designing instructional materials that is the focus of my
study.
First, knowledge of students’ understanding of science is the foundation of teacher
knowledge, concerning how deeply they are aware of students’ understanding of a specific topic.
Knowledge of science learners involves understanding students’ learning difficulties, students’
misconceptions, students’ prior conceptions from previous learning experiences, different
requirements for learning certain concepts, and approaches to learning science in general. Abell
(2007) reviewed that research has shown that many teachers did not acknowledge students’
common misconceptions and inadequate understanding of scientific topics among students (e. g.
Halim & Meerah, 2002). Teachers should be able to use their knowledge on students awareness
of particular topics to plan their lessons, rather than basing their lesson plans only on their
personal views of the subject (Hill, Ball, & Schilling, 2008). In other words, it is extremely
important for researchers to understand how much teachers know about their students’
understanding. To study teachers’ knowledge of learners, researchers used a series of
hypothetical cases of students’ scientific learning and misconceptions, that teachers are asked to
identify learning challenges and explain student learning (e.g. Stocklmayer & Treagust, 1996).
Second, knowledge of science instructional strategies comprise of subject-specific
strategies (e.g. learning cycle, use of analogies, or demos or labs) and topic-specific strategies,
including representations (examples, models, and metaphors), demonstration, and activities (lab,
22
problems, cases). Researchers have demonstrated that while knowledge of instructional strategies
is linked to SMK and knowledge of learners, it also requires a strong understanding in the
strategy at hand(Clermont, Borko, & Krajcik, 1994; Clermont, Krajcik, & Borko, 1993).
As a result, my research focuses on teachers’ knowledge in using representations and
other possible strategies to teach multiple models of genes. Many existing studies have explored
topics relevant to this research. For example, Hellamy (1990) found that teachers’ PCK in
genetics teaching was similar among participants in terms of using common teaching sequences
and activities (as cited in Abell, 2007). Van Driel, Jong, & Verloop (2002), on the other hand,
explored the knowledge of pre-service chemistry teachers on teaching strategies about models
and modeling when they taught the particle concept. Their findings showed that pre-service
chemistry teachers had the tendency to jump between macro and micro levels without
considering its impact toward students’ understanding. In addition, Sperandeo-Mineo, Fazio, &
Tarantino (2005) found that teachers have similar learning difficulties with students regarding
representations in thermodynamics topic.
While the research has been extensive, the continual challenge for researchers, however,
is that PCK is a tacit and hidden knowledge (Kind, 2009). Although the conceptual framework of
PCK has been developed, finding out exactly what it looks like and how to apply this knowledge
to support good practice in science teaching is not easy. PCK is tacit knowledge that is often not
used consciously as an explicit tool by teachers in designing lessons; in other words, teachers
may not be aware of the process they are undertaking. To ameliorate this difficult situation, this
study applied multiple methods to elicit teachers’ PCK, which has led to an intensive data
collection process.
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Conceptual Framework
A conceptual framework outlines a set of interrelated theories, variables, and relations
that frame the basis for this research study, in conjunction with the development of the research
questions (see Figure 1). This study defines the condition in genetic education, and proposes
pedagogical intervention in light of the particular expected outcomes.
The underpinning theoretical perspective of this research is guided by research on
scientific models. The literature on scientific models offers a framework to analyze the abstract
and complex gene in hopes of understanding students’ conceptions of the gene. The classical and
molecular models are often divided into the classical genetics and molecular genetic domains. In
each domain, scientific ideas, practices, and questions are guided by the particular model.
Under this condition, the study aims to develop pedagogical tools to remedy the
identified problem on students’ lack of connections between the gene models to foster a more
comprehensive understanding, by creating curricular and instructional supports to help students
link the two models. The desired outcome is postulated for guiding design principles. The
literature on expert knowledge suggested that students’ mastery in solving genetics problem will
happen when students have integrated knowledge of the two models, apply the models in
appropriate contexts, and flexibly retrieve the models to solve problems.
In order to boost such integrated knowledge and skills, the development of these
pedagogical tools is guided by the aforementioned principles and frameworks, including the
multiple representation principles, teacher content knowledge, and teachers’ PCK. Multiple
linked representations that simultaneously combine classical and molecular representations could
support students connect ideas about genes, proteins, and phenotypes; pedagogical tools can
provide explicit links, concurrent visual presentation, and application in contexts.
24
Figure 1. Conceptual framework of the study.
Classical Model
Molecular Model
Disconnect Connect
Condition Intervention (Q1, Q2, Q4) Desired Outcome (Q3)
Pedagogical tools
• Integrated knowledge • Contextualized application • Flexibly retrieve
Classical
representations Molecular
representations
Protein Phenotype
Multiple linked representations • Explicit links • Concurrent presentation • Application in contexts
Scientific Models
Expert & novice knowledge
Design-based research
Multiple representations
Teacher content knowledge
Teacher PCK
Gene Classical
Model Molecular
Model
Note. The shaded box indicates the gene model. The box indicates the literature conceptualizing particular piece.
25
Part III: Science Education in Thailand
Because this study took place in Thai classrooms with Thai teachers, students, and
curriculum, some overview of the science education in Thailand is necessary. This section
outlines Thailand’s education system, its high school science education, and any relevant
education issues in Thailand.
Thailand’s Education System
Education in Thailand has undergone a comprehensive reform as a result of the 1999
National Education Act. While in the past, the substance of Thai education was mainly
determined by the Minister of Education, the National Education Act introduced reform
initiatives that emphasized the decentralization of educational authority to local communities and
schools. The stated purpose of these reforms is to provide equity and quality in education and to
increase the quality of life of the Thai people. As a result of these reforms, the state now provides
twelve years of free basic education to each individual (Office of the Education Council (OEC),
2008). Basic education covers pre-primary, six years of primary education, three years of lower
secondary education, and three years of upper secondary education (see Figure 2). Only nine
years of primary and lower secondary education are compulsory.
Following the decentralization of educational administrative authority, the country is
currently divided into 185 educational service areas in 76 provinces. Each educational service
area is responsible for approximately 200 educational institutions, in which there are around
300,000-500,000 students. Each school is responsible for its own administration and
management relating to academic matters, budgets, personnel, and general affairs.
26
Figure 2. Structure of the education system in Thailand (OEC, 2008)
While districts are divided and have their respective administrative mechanisms, there
continues to be a national curriculum. The Basic Education Core Curriculum 2008 (BEC) was
developed as the national curriculum and has served as provision of education of all types,
covering all target groups of learners with basic education (Office of the Basic Education
Commission (OBEC), 2008). This curriculum provides local communities and schools the
framework to prepare their respective school curricula, where communities are free to design
based on their particular environments, cultures, and demographics to serve local needs and
contexts. The national core curriculum was officially implemented at all schools in 2010 and
covered all grade levels by 2012. The curriculum stipulates goals, desired learners’ key
competencies, and standards of eight learning areas (See Figure 3).
27
Figure 3. Relationship in the development of learners’ quality according to the Basic Education
Core Curriculum (OBEC, 2008).
Relationships in the Development of Learners’ Quality According to the Basic Education Core Curriculum
Desired Characteristics 1. Love of nation,religion and the monarchy 2. Honesty and integrity 3. Self-discipline 4. Avidity for learning 5. Applying principles of Sufficiency Economy
Philosophy in one’s way of life 6. Dedication and commitment to work 7. Cherishing Thai nationalism 8. Public-mindedness
Goals 1. Morality, ethics, desired values, self-esteem, self-discipline, observance of Buddhist teachings or those of one’s faith, and applying principles of Sufficiency Economy Philosophy; 2. Knowledge and skills for communication, thinking, problem-solving, technological know-how, and life skills; 3. Good physical and mental health, hygiene, and preference for physical exercise; 4. Patriotism, awareness of responsibilities and commitment as Thai citizens and members of the world community, and adherence to a democratic way of life and form of government under a constitutional monarchy; and 5. Awareness of the need to preserve all aspects of Thai culture and Thai wisdom, protection and conservation of the environment, and public-mindedness with dedication to public service for peaceful and harmonious coexistence.
Vision The Basic Education Core Curriculum is aimed at enhancing capacity of all learners, who constitute the major force of the country, so as to attain a balanced development in all respects – physical strength, knowledge and morality. They will fully realize their commitment and responsibilities as Thai citizens and members of the world community. Adhering to a democratic form of government under a constitutional monarchy, they will be endowed with basic knowledge and essential skills and favorable attitude towards, further education, livelihood and lifelong learning. The learner-centered approach is therefore strongly advocated, based on the conviction that all are capable of learning and developing themselves to their highest potentiality.
Learners’ Key Competencies 1. Communication Capacity 2. Thinking Capacity 3. Problem-Solving Capacity 4. Capacity for Applying Life Skills 5. Capacity for Technological Application
Learning Standards and Indicators Learner Development Activities for Eight Learning Areas
1. Thai Language 2. Mathematics 3. Science 1. Counseling activities 4. Social Studies, Religion and Culture 2. Student activities 5. Health and Physical Education 6. Art 3. Activities for social and public interest 7. Occupations and Technology 8. Foreign Languages
Learners’ quality at basic education level
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fostering self-development. Instruction time for upper secondary education is allotted on a
semester basis, no less than six hours a day; the regular school period is 8AM to 4PM, and each
class period lasts about 50 minutes. The minimum time allotted to 10th to 12th grade students for
science education is 240 hours with the criterion of at least 40 hours per semester. Educational
institutions can increase the allotment of time, depending on their readiness and priorities, to suit
their contexts and learners’ situations.
Another important context about the Thai education system is that Thai high school
students are assigned to different tracks according to the respective systems in each school.
Students’ placement is based on their academic achievement and interests in advanced classes,
and classes in subjects like science-math, science-engineering, English, and other language arts.
This study focuses on students in the science track who intended to pursue higher education in
pure science, applied science, and other science-related areas. In the Science track, students are
required to take Science coursework beyond the minimum requirement. In addition, students take
Biology, Physics, and Chemistry together in every semester. The learning time for Biology is
about 80 hours per semester.
High School Genetics
This section focuses on high school genetics in the BEC and in the advance science
curriculum in Thailand. The science subject areas that all students should learn consist of eight
principal sub-strands, such as living organisms and living processes, life and the environment,
and the nature of science and technology. Subject areas progress from simple to more complex
content in ascending grade levels. Instructions and assessments are expected to build the
foundation for students so that continuity and connectivity in science are developed and
maintained. The rationales for learning science presented in the national curriculum include the
29
followings: the importance of science as part of the world culture; the relationship between
science and our everyday life; the benefits reaped from scientific knowledge; the cultivation of
thinking skills, investigative skills, problem-solving ability, and verifiable decision making
skills. It is stated that “All of us therefore need to be provided with scientific knowledge so as to
acquire knowledge and understanding of nature and man-made technologies and to apply them
through logical, creative and moral approaches” (OBEC, 2008, p.104).
Examples of learning indicators and core content standards related to genetics for
secondary school defined in the BEC are presented in the table below (See Table 2); these
standards are mandated for all high school students. Indicators specify what learners should
know and be able to perform, as well as their intellectual; characteristics for each grade level;
Interval Indicators direct the learning standards for upper secondary education level (grades 10 to
12). Note that there are no indicators relating to genetics in grade 7 and 8 (OBEC, 2008)
Table 2
Indicators Relating to Genetics from Secondary School Science Curriculum.
Science: Application of knowledge and scientific processes for the studying and discovery of knowledge; systematic problem-solving; logical, analytical and constructive thinking; and scientific-mindedness. Strand 1: Living Things and Life Processes Standard Science1.2: Understanding the process and the importance of genetic transmission, the evolution of living things, biodiversity, the application of biotechnology in relation to humans and the environment. Incorporating investigative processes for seeking knowledge and scientific reasoning, and the ability to transfer and apply knowledge into practice.
Grade-level Indicators (Grade 9) Interval indicators(Grade 10 to 12) 1. Observe and explain the characteristics of chromosomes with genetic units or genes in their nuclei. 2. Explain the importance of genes or DNA and the process of transmitting genetic characteristics. 3. Discuss genetic diseases resulting from abnormality of genes and chromosomes, and
1. Explain the processes of genetic transmission, transformation, mutation and the origin of biodiversity. 2. Search for data, discuss the effects of biotechnology on human beings and the environment, and put it into practice. 3. Search for data and discuss the effects of biodiversity on human beings and the
30
put it into practice. 4. Explore and explain biodiversity in a local area that enables living organisms to maintain a balance of life. 5. Explain the effects of biodiversity on human beings, animals, and plants. 6. Explain the effects of biotechnology on the lives of human beings and the environment.
environment. 4. Explain the natural selection processes and their effects on the diversity of living things.
The advanced science curriculum for students in the science track is endorsed by the
Institute for the Promotion of Teaching Science and Technology. 1 Expected learning outcomes
cover broader and more advanced subject matters. In the genetics unit at the end of the higher
secondary level. the student should be able to search for information, analyze, discuss, explain,
and draw conclusions about: a) Mendel’s principles of genetic inheritance; b) Mendelian genetics
and genetic variation; c) chromosome, structure and function of genetic materials; d) properties
of genetic materials; e) mutation and its results; and f) DNA technology and applications (IPST,
2001). Due to the flexibility of interval standards, schools may organize contents for each
semester varyingly.
Issues of Science Education in Thailand
Thai education is in the midst of rapid and dramatic growth and change. Among these
changes, some have been purposefully designed, while others are unintended but have occurred
in response to the interplay of social actors. While Thailand has received noteworthy praise for
its successful efforts in expanding access to education and in raising the level of educational
attainment by international standards, the quality and equality of Thai education are still in
question (IPST 2010). This section addresses some major concerns over the Thai science
education. 1 The Institute for the Promotion of Teaching Science and Technology (IPST) is a national institution which comes under the direction of the Ministry of Education, Thailand. This organization is responsible for initiating, promoting, and conducting studies on curriculum development, professional development, teaching-learning methodology, instructional materials, and evaluation of science, mathematics and technology education on all levels.
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Overpopulated classroom. In public high schools, the student/ science teacher ratio is
approximately 47 students per instructor. An overpopulated classroom can affect teacher-student
interactions, teaching strategies, group activities, and student motivation. Although the ratio has
been reducing promisingly, it is still high compared to other countries. Note that in my study the
observed classrooms were mainly all males; this is not a representative population of Thai
students; the gender parity index in secondary level enrollment is 1.08 in 2011 (UN, 2012).
Due to the high students/teacher ratio, there is a shortage of qualified teachers in
Thailand, especially those with training background in science subject areas (Dechsri,
Eamsukkawat, & Ketwadee, 2008). At the upper secondary education level, most teachers teach
subject areas relevant to their training backgrounds.
Teacher development. Professional development programs for science teachers are
mainly offered by the Ministry of Education, Thailand; IPST, in particular, has a mission to
develop materials and programs for the professional development of teachers and educators in
science, mathematics, and technology. These training activities mainly focus on improving
teachers’ academic capacity in particular subject areas and pedagogy methods. IPST has
endeavored to incorporate the inquiry approach in science teaching; however, lecturing and
memorizing facts are still persistent in many classrooms. Moreover, Thai teachers’ salaries are
rebuked to be insufficient to meet their basic needs. Thai teachers are often overworked due to
excessive administrative duties; as a result, they have very little time left to prepare classroom
activities.
Science learning achievement. Talented Thai students who succeeded in getting medals
from the International Science and Mathematical Olympiads as presented in the news almost
every year (The Nation, 2013); however, the majority of students have relatively low
32
achievement in science and mathematics, compared to other countries. If we examine how well
Thai students have performed on international comparative studies, the issue is apparent. Results
from the TIMSS and PISA assessments suggest that Thai secondary education students perform
below the average set by students in other participating nations (Dechsri et al., 2008).
University Admission. In Thailand, admission to higher education institutions is viewed
as an important stage by mainstream society. The main critique of higher education is that the
university entrance system works against high school educational policies and goals. University
entrance tests focus mainly on factual content knowledge posting a major hurdle to how teachers
teach in the class, and more importantly, how students learn and what their motivations are.
Students have demonstrated that they are more interested in passing the examination only as a
means to being admitted to a certain university. The admission system to the university level in
Thailand has undergone many major revisions and experiments since 2001. The system has
changed from single test, multiple tests, Central University Admission System2, to the current
Admission System3. The current university admission system has been critiqued by students,
parents, schools, and universities due to the unsettling changes and failure in evaluating student
performance. Several higher educational institutions would offer direct admission through a
system launched by the university itself, instead of using the central admission system supervised
by the National Institute of Educational Testing Service.
Shadow education. Outside of a school system, a dense network of academic institutions
consisting of tutors and exam prep schools also exists for boosting academic performances in
2 Launched in 2006, Central University Admissions System contains: O-NET (Ordinary National Educational Test), A-Net (Advanced National Educational Test), GPAX and GPA. 3 Launched in 2010, Admission System comprises: the compulsory General Aptitude Test (GAT) that covers reading, writing, analytical thinking, problem solving, and English communication; and the voluntary Professional Aptitude Test (PAT) that has a choice of seven subjects.
33
schools and for preparing students for university exams. The enormous amount of emphasis on
university exams has put pressure on students, parents, teachers, and schools. Seeking well-
known tutors and supplementary curriculum through private tutoring seems to be the answer for
many students and parents. This additional education is offered from the elementary all the way
to the high school level across the nation; exam prep schools are particularly popular among high
school students preparing for university admission. Teaching in these contexts usually involves
practicing tests, remedial assistance, and lecturing. This additional education outside of formal
schooling tends to shadow student learning in their own schools. Students who utilize and rely on
private prep schools may suffer a lack of interest during their regular class periods, and teachers
may choose not to fully devote their knowledge in the formal classroom setting.
Educational resources. The government’s budget for education in 2009 was 4.1% of
the national gross domestic product; it as accounted for 21.8% of the national budget (MOE,
2012). Although by allocating 20% of its annual budget to education, Thailand is already among
the world’s top education spenders relative to its size, its investment plans on school resources,
technology, and scholarships had been intensively critiqued. Many critics raised concerns about a
deficiency of support on teacher development and on the content of classroom education
(Reuters, 2011). In addition, while some classrooms face a shortage of instruments and resources
for science teaching, resources are not always fully utilized in some other classrooms.
Socioeconomic/Cultural Contexts. Unlike the American education system, racial,
ethnic, and language diversity issues are not dramatic tensions in Thai education. Thailand's
population is relatively homogeneous, sharing a common language and national religion.
Instruction in schools is offered in Thai, the official language of the country. A recent movement,
34
in establishing the Association of Southeast Asian Nations anticipated to materialize in 2015, has
prompted an increasing number of schools integrate English into daily instructions.
In addition, Thailand boasts a consistently high adult literacy rate of 94%, which is high
comparing to other developing countries (United Nations Children's Fund (UNICEF), 2012). The
problem on equity and quality education, however, largely stems from socioeconomic factors.
Disparities among students from poorer-rural and richer-urban areas are one of the main
challenges because educational achievements have been found to be positively correlated with
household resources, the educational level of the head of family, and the size of the school, and
negatively correlated with the size of the classroom and the student-teacher ratio (The World
Bank, 2006).
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CHAPTER 2: Literature Review
Disconnected Multiple Models of the Gene in the High School Curriculum
Introduction to the Chapter
“What is a gene?” High school students respond to this question with a wide range of
answers: it is a unit of heredity; it is something passed from parents; it is part of a chromosome;
it is a sequence of nucleotides; and it is information for determining a trait. To some extent, all of
these answers correctly describe what a gene is. Students may take away one or many of these
different meanings from the classroom. As science educators, it is important for us to ask which
of these definitions we want students to take from their formal education in science and what
ideas students need to understand in order to make sense of current science they encounter will
after they leave schools.
In order to prepare scientifically literate students, science curricula need to be updated to
match the developments of science; they must also be related to the ideas people are exposed to
in everyday life (Rutherford & Ahlgren, 1991). Yet many high school biology teachers confine
most of their instruction in genetics to teaching students about monohybrid and di-hybrid
crosses, wrinkled and round peas, and the ratios you can expect between tongue rollers and non-
tongue rollers. Such instruction in what is commonly referred to as transmission genetics or
classical genetics (Waters, 2004) has little to do with the kind of genetics concepts students are
likely to encounter in current everyday science.
The field of genetics has been rapidly progressing, and most of its more recent
development involves an understanding of biochemical interactions and structures at the
molecular level. With their new knowledge of molecular genetics, scientists have been able to
study genetic inheritance, evolution, diseases, and other related phenomena more effectively.
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Molecular genetics has become a part of everyday life through its applications in medicine,
agriculture, and environmental sciences. For example, we are now able to prevent diseases by
identifying their DNA sequences. We eat genetically modified organism such as corn and soy
that contain sequences engineered to improve traits such as resistance to parasites. Scientists now
explain genetic phenomena by describing genes as sequences of instructions: genes contain
genetic information that brings about genetic traits. This view of genes is related to, but distinct
from, the most common idea that students take away from their classes: a gene is something
passed from generation to generation.
If we want to prepare students to engage with contemporary genetics and to be informed
citizens, understanding genetic phenomena solely through a classical genetics lens is no longer
sufficient. However, Condit (2010) showed that the average citizen still “understands genetics
through the lens of heredity, not in terms of the structural and functional nature of genes” (p. 1).
Condit predicts that this problem could foster a belief in genetic determinism and possibly lead
to discriminatory attitudes in the public. The public’s understanding of genetics is commonly
limited to the idea that genetic traits are transmitted through familial relations. In other words,
the public does not necessarily conceptualize genes as sequences of instructions and understand
how genes control traits along with environmental factors.
The problem in genetics education, then, is that current curricula fail to prepare students
to make sense of contemporary genetics, in which the emphasis is placed on the molecular level.
The literature showed that most high school students struggle to make sense of genes as
sequences of instructions, which helps explain why they also struggle to apply their ideas about
genes to explain genetic phenomena (e.g. Auckaraaree, 2010; Duncan & Reiser, 2007; Tsui &
37
Treagust, 2004; Tsui & Treagust, 2007; Venville, Gribble, & Donovan, 2005; Venville &
Treagust, 1998).
The purpose of this chapter is to shed light on the following question: Why do many
students fail to develop an understanding of the molecular gene? First, this chapter reviews
challenges identified in education research that students face in learning genetics, especially
regarding ideas about what a gene is. Second, the chapter explores the gene concept in light of
different historical and conceptual theories. The analysis was informed by a scientific modeling
framework according to which we understand science through the use of scientific models.
Finally, I discuss problems with the way the gene concept is presented in current high school
textbooks and offer guidelines for designing learning materials that promote meaningful
understanding of the gene.
The review unveiled that the current biology curricula contain multiple models of the
gene for explaining genetic phenomena; however, these models are presented disconnectedly in
different explanatory domains, classical genetics and molecular genetics. My main argument is
that students who are unable to make logical and meaningful connections among multiple
models of the gene will be incapable of understanding genetics phenomena meaningfully.
Without connections between the classical and molecular models, the students are unlikely to
develop a basic knowledge about the molecular model and explain genetic problems across
domains necessary for a complete understanding of genetics. It is imperative that students be
able to develop connections between models because: a) both models, though distinct, represent
one gene concept and are complementary for explaining genetics phenomena; and b) students
can effectively retrieve and appropriately apply their knowledge when it is integrated and
organized (DiSessa, 1982; NRC, 2005). The following example illustrates that an integrated
38
understanding of multiple models empowers a student to reason about promoting his own health.
For example, a student believes that his family has a sickle cell anemia trait. He applies the
classical model to make predictions about probability of getting the trait and the molecular model
to offer an explanation for causes and to conduct some viable research on treatments. Offering an
explanation based on both models creates more meaningful explanation, not limited to
deterministic perspective on genetic traits.
Students’ Understanding of the Gene Concept
Genetics is a requirement dictated in the high school curricula by most national standards,
including those in the U.S. (NRC, 1996; Rutherford & Ahlgren, 1991) and in Thailand (IPST,
2001). According to these national standards, students are expected to understand genetic
inheritance, molecular genetics, and the role of genetic technology. While genetics is one basis
of biology, genetic concepts are challenging to both students and teachers (Stewart, 1983; C.
Tsui & Treagust, 2004). Several studies on genetic literacy show that students have difficulty
learning genetics across all educational levels including elementary school (Wood-Robinson,
Lewis, & Leach, 2000), middle school (Zohar & Nemet, 2002), high school (Kindfield, 1994;
Venville & Treagust, 1998), and at the university (Duncan & Reiser, 2007).
What is challenging about learning genetics? Previous research on students’
understanding of genetics focused primarily on Mendelian genetics—a scientific explanation of
how traits are passed from parents to offspring—and in particular on student cognition and
problem-solving (e. g. Lewis & Kattmann, 2004; Lewis, Leach, & Wood-Robinson, 2000; James
Stewart, 1983; Jim Stewart & Van Kirk, 1990; Tsui & Treagust, 2007; Venville et al., 2005;
Venville & Treagust, 1998; Wood-Robinson et al., 2000). Few studies documented teaching and
learning molecular genetics, and most studies were focused to the university level (e.g. Duncan
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& Reiser, 2007; Friedrichsen & Stone, 2004; Marbach-Ad, Rotbain, & Stavy, 2008; Rotbain,
Marbach-Ad, & Stavy, 2006). These studies identified various factors that lead to challenges in
learning genetics:
• Genetics involves abstract, invisible, and complex phenomena that students cannot
directly experience (Kindfield, 1992).
• Genetic phenomena entail reasoning at multiple levels of biological organization from
cells, tissues, and organs, to organisms and populations (Malacinski & Zell, 1995). In
addition, Duncan and Reiser (2007) proposed that understanding genetics problems
involves reasoning at multiple levels: physical level (cells, proteins, organs) and
informational level (genes). Students are required to make connections between these
multiple levels to explain genetic phenomena.
• Students have a fragmented knowledge of major concepts in genetics (genetic
materials, proteins, and phenotypes). Without meaningful connections at the structural
and functional levels, students cannot explain genetic phenomena. To illustration, the
researchers identified disconnections among the following entities: alleles, genes and
chromosomes (Lewis & Wood-Robinson, 2000); the structure and function of genetic
entities (Marbach-Ad et al., 2008; Marbach-Ad, 2001; Rotbain et al., 2006); genes and
proteins (Duncan & Reiser, 2007), including genotype and phenotype (Lewis &
Kattmann, 2004).
• Students are unaware of underlying mechanisms that bring about genetic phenomena
(Duncan, 2007); as a result, they demonstrate the fragmented knowledge addressed
above. In Mendelian genetics, students’ difficulty understanding transmission genetics
is due to a lack of understanding of the cellular mechanisms underlying patterns of
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inheritance, mitosis, and meiosis (Finley et al., 1982; Stewart & Van Kirk, 1990;
Wynne et al., 2001). In molecular genetics, students’ difficulty in understanding gene
expression is due to a lack of understanding of protein synthesis and the function of
proteins in phenotypes (Duncan & Reiser, 2007).
• Learning about genetic phenomena requires an understanding of other subjects such as
probability in order to explain patterns of inheritance, and an understanding of chemical
and physical interactions at the molecular level in order to explain molecular genetics
(Duncan, 2007).
• Another problematic issue pertains to genetic determinism. Many students have the
misconception that one gene is always responsible for one trait and are unaware of
polygenic inheritance and environmental factors that determine phenotype (Mills Shaw,
Van Horne, Zhang, & Boughman, 2008).
• As with other topics from biology, learning genetics is complicated by unfamiliar and
extensive scientific terminology (Banet & Ayuso, 2003; Lewis & Wood-Robinson,
2000).
What is challenging in learning about genes?
Importantly, research revealed that students have difficulty understanding even the core
concept of genetics—the gene concept (a unit of inheritance of the living organism). The gene is
a conceptually complex entity that scientists use to explain biological attributes and functions. It
is a basic concept students need to understand in order to explain genetic phenomena; however,
most students do not have a concrete understanding of the structure, location, and function of
genes (Lewis & Kattmann, 2004; Marbach-Ad, 2001; Venville et al., 2005).
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Researchers mainly applied a conceptual change theoretical framework in exploring how
students conceptualize the gene in order to understand the ways students make sense of genetic
phenomena (Duncan & Reiser, 2007; C. Tsui & Treagust, 2007; Venville & Treagust, 1998).
According to a conceptual change theory grounded in constructivism, learning is the process of
change from prior misconceived knowledge to correct knowledge (Chi, 2008). Learners
construct new knowledge based on their prior knowledge and experiences in ways that are
coherent and useful to them. The learners’ conceptual ecology—including ideas, commitments,
and beliefs—provides the context within which conceptual change occurs (Hewson, 1981;
Posner, Strike, Hewson, & Gertzog, 1982). To experience conceptual change, learners become
dissatisfied with their current conceptions and accept alternative ones. A learners determine the
status of a new conception according to whether it is intelligible (knowing what it means),
plausible (believing it to be true), and fruitful (finding it useful) (Duit & Treagust, 2003).
Venville and Treagust (1998) proposed a promising framework for examining conceptual
change in the genetics understanding of grade 10 Australian students in understanding genetics.
The developed framework based on Martins and Ogborn (1997), demonstrates ontological
changes in the way that students saw genes : a) from being passive to being active; and b) from
being particle-like to being a sequence of instructions (see Figure 4). Venville and Treagust
(1998) organized students’ conception of genes into four conceptual statuses:
1. Passive particle gene: genes are things that get passed from parents to offspring.
2. Active particle gene: genes are sections of chromosomes that control characteristics.
3. Sequence of instructions gene: genes consist of codes for determining traits.
4. Productive sequence of instructions: genes are sequences of nucleotides that produce
proteins to control phenotypes
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Figure 4. A pathway indicating the students’ progress through progressively more sophisticated
mental models of gene (Venville and Treagust, 1998, p. 1040).
Venville and Treagust’s work (1998) demonstrated that most students failed to change
their conceptual idea of the gene as a particle gene to the preferred one of the gene as a
productive sequence of instructions, even after completing a targeted curriculum on molecular
genetics. The results showed that only four out of 79 students held a sophisticated concept of the
gene as being a set of sequences of instructions and that none of the students identified the gene
as the productive sequence of instructions. The majority of students described genes as segments
of DNA or chromosomes that control phenotypes. For example, students conceptualized the gene
as a particle that controls hereditary traits, but they did not understand the molecular function of
the gene to attribute such traits. Their conceptions of the gene were thus intelligible (knowing
what it means), partly plausible (believing it to be true), but not fruitful (finding it useful).
However, after instruction, students’ conceptions did change from the gene as a passive particle
to the gene as an active particle. The authors concluded that changing conceptions across the
ontological categories from a particle conception to a sequence of instructions conception is
more challenging than elevating conceptions within an ontological category from the gene as
passive to the gene as active.
Other studies have applied this framework to study student knowledge and conceptual
change of genetics. For example, Tsui and Treagust (2004) examine the conceptual learning of
genetics in a grade 10 Australian classroom (n=23) that learned genetic inheritance with
passive particle gene
active particle gene
sequence of instructions gene
productive sequence of instructions gene
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BioLogica, a computer-based multiple representations teaching intervention. The study revealed
the similar result that, after formal teaching, only two students mentioned genes as being a
sequence of instructions conveying information for protein synthesis. The authors explained that
conceptions of genes as particles belong to the ontological category of matter and conceptions of
genes as sets of productive sequences of instructions for protein synthesis belong to the category
of processes. The authors proposed that “students have the natural preference to think of
concepts as matter-based rather than process-based” (p.187).
Tsui and Treagust (2007) investigated the conceptual change of students in grades 10 and
12 in three Australian senior high schools where the teachers integrated BioLogica in the
classroom. A cross-case analysis of conceptual statuses of students’ conceptions of the gene
indicated that, after instruction, only four out of the 26 students only four students held
conceptions which were intelligible, plausible, and fruitful. Moreover, the results of the post-test
showed that only seven out of 75 students stated that “A gene is information for making
proteins” (classified as a productive sequence of instructions conception); most students stated
that “A gene determines a trait/characteristic” (classified as an active particle conception).
Focusing on different aspects of student understanding, Duncan and Reiser (2007)
examined students’ reasoning on molecular genetics, particularly on how genes bring about
traits. Participants were grade 10 students from an urban public high school in the Midwestern
United States. The results demonstrated that, before instruction, only 12 of 64 students
mentioned genes as sequences of instructions and in the post-test the number of students who
defined the gene as a sequence increased from 12 to 24. None of the responses, however,
belonged to the category of genes as a productive sequence of instructions. Although a greater
percentage of students demonstrated understanding of genes as sequences of instructions, as with
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other studies, the number of students with a molecular understanding of the gene remains
unacceptably low.
In summary, the studies reviewed here revealed similar results that most students viewed
the gene as a particle and that after formal teaching their conception did not change to another
ontological level of the gene as a sequence of instructions (Duncan & Reiser, 2007; C. Tsui &
Treagust, 2007; Venville et al., 2005; Venville & Treagust, 1998). The lack of a meaningful
understanding of genetics has been documented worldwide in various educational contexts,
including the United States, Australia, and Thailand. Venville and Treagust (1998) commented
that a conception of the gene as a particle is necessary in order for students to make sense of
fundamental genetics; however, the absence of a more sophisticated understanding of the gene as
a sequence of instruction will hinder students’ understanding of genetics phenomena, especially
regarding the central dogma (i.e. DNA in genes codes for RNA that is translated into proteins).
My master’s thesis (2009), conducted surveys with 97 Thai high school students,
confirmed that after instruction a majority of students viewed the gene as an active particle but
that only ten students demonstrated an idea of the gene as a sequence of instructions gene (see
Table 3). The results also showed that individual students could hold multiple views of genes
when they explained genetic phenomena in different contexts; as an illustration, one student
applied the concept of the gene as a sequence of instructions in order to explain gene expression
and applied the concept of the gene as a particle in order to explain genetic inheritance (see
Table 4).
Importantly, the findings confirmed Venville and Treagust’s claim (1998) that the
absence of students’ conception of the gene as a sequence of instructions hindered their
understanding of gene expression. Compared to those who had the conception of genes as
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Table 3
Examples of Students’ Responses and Students’ Conceptions of Genes Categories
Conception of Genes Examples of Students’ Responses Number of Students (N=97) (%)
Passive particle gene Genes are the genetic material passed from parents. 9 (9.28)
Active particle gene Genes are units of inheritance in organisms. The function is to control genetic traits of organisms.
76 (78.35)
Sequence of instructions gene
Genes are regions of DNA that contain specific information for each part of the body in organisms.
4 (4.12)
Productive sequence of instructions gene
Genes are units that control protein synthesis in the body. Genes bring about the expression of traits.
6 (6.19)
Others responses - 2 (2.06)
Note. The results are from Auckaraaree (2009). particles, students who held a conception of the genes as a sequence of instructions could explain
more accurately how genes control genetic traits through protein synthesis. However, the
understanding of protein synthesis did not differ significantly between students who held a
conception of the gene as being active and those who held one of the gene as being passive.
Students who held a conception of the gene as an active particle understood some functions of
genes, such as transmitting hereditary traits; however, this understanding did not ensure that
students knew underlying molecular processes of gene expression.
Furthermore, the results confirmed that students often do not realize that genetic
phenomena are inevitably mediated by proteins (Duncan & Reiser, 2007). The students in my
master study failed to elaborate the role of proteins as a mediator between genes when they
solved problems about gene expression (Auckaraaree, 2009). Friedrichsen, Stone, and Brown
(2004) argued merely changing a conception to “genes coding for proteins” is not enough
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Table 4
Examples of Students’ Response about the Meaning and Function of Genes.
Note. Students’ responses are selected from the interview in order to illustrate the influence of students’ conception of genes on their reasoning about gene expression.
Category Conception of Genes Particle Gene Sequence of Instruction Gene
A meaning of genes Nancy: a gene is the unit of inheritance that can be transferred to next generation.
Kate: Genes are DNA. It is a long polynucleotide. Genes are sections of DNA. If DNA is very long strand, genes are regions of that long strand. These sections will be used for coding to produce proteins in order to control genetic traits of us. Genes are nucleic acids connected to be a strand and that strand can be translated to the genetic code.
Representations of genes
Explanation of how genes control genetic traits
Sandy: Is this related to cells? Controlling traits. I think it is about proteins or something as a composition. And, it is related to activities in our body. It (a gene) is transferred from parents to build us looked like this. …How do genes control the expression? What should it be? They (genes) are like a structure of us, inside, very deep in cells or something. They are in every parts of the body in organisms.
Joe: The function, it is genetics. It seems like our body has protein synthesis from nucleus via RNA. RNA comes from DNA. It is a transcription and then it is a protein synthesis. It is like transcription from DNA and then producing protein like enzyme in our body. This brings about expression of characteristics in many ways
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and non-science major college students failed to understand the roles of proteins in cell
mechanisms. Protein knowledge is essential for reasoning across the levels of genetic
phenomena from the information level to the physical level (Marbach-Ad et al., 2008; Rotbain et
al., 2006). Without an integrated knowledge of genetic information, proteins, and traits, some
students consequently viewed genes and hereditary traits as equivalent (Auckaraaree, 2009;
Lewis & Kattmann, 2004; Venville et al., 2005). This problem could lead to an overly
deterministic perspective due to the lack of awareness of gene expression and mutation.
The Gene Concept as Multiple Scientific Models
Although, the previous research has provided a decent beginning point for an analysis of
student understanding of genes, it is limited by its reliance on the conceptual change theory in
interpreting students’ knowledge of genes. To explain what prevents students from retaining the
sequence of instructions gene concept, I propose that research on the gene concept should draw
on the scientific modeling theory, reconceiving these distinct conceptions of the gene as multiple
models, each of which is fruitful in its context. I will provide a brief description of scientific
models and explain why conceptual change gives an incomplete account of learning the gene
concept.
What is a scientific model? Scientific modeling and models are essential elements of
scientific practice that enable scientists to develop an understanding of how the natural world
works. Scientific models are schemes or structures that correspond to complex phenomena in
nature, making abstraction visible and providing the basis for explanations and predictions about
scientific phenomena (Gilbert, 2005; NRC, 1996; Passmore & Stewart, 2002). Scientific models
or conceptual models, as scientific knowledge, represent real matters and processes of the
phenomena in the physical world in the form of representation and symbols (Hestenes, 2006).
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For example, scientific models of the gene as a unit of inheritance represent real matters of
genetic materials and entail genetic code for gene expression processes. Since a model is limited
to depicting only particular aspects of reality, multiple models of the same phenomenon can be
produced to help explain data and patterns that develop as new discoveries are made.
Geneticists observe natural phenomena about genetics in the physical world, interpret
data, and generate scientific models of the gene in order to represent and interpret particular
processes (see Figure 5). Scientific models are then used and disseminated in the scientific
community, often though the use of representations (Hestenes, 2006). In science classrooms,
scientific models are presented to students as cultural artifacts to help them learn about scientific
phenomena. Through discourse, students learn to explain scientific phenomena and solve
problems by using scientific models as tools for the construction of ideas (Driver et al., 1994).
Since students cannot directly experience genes, they construct mental models representing these
microscopic phenomena according to scientific models of genes represented in the curriculum.
Figure 5. The framework of the relationships among mental models, conceptual models, and
physical world (Hestenes, 2006)
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The rationale for using models as analysis framework. Based on conceptual change
theory, the reviewed studies concluded that a majority of students finished their genetics course
with a conception of the gene as an active particle, which was classified as intelligible, partly
plausible, but not fruitful (Dawson & Venville, 2011; C. Tsui & Treagust, 2004, 2007; Venville
& Treagust, 1998). I argue that an understanding of genetics is incomplete without both
conceptions of the gene and that both conceptions are equally important for students. It is
misleading to describe a particle conception of the gene as an alternative idea or a misconception
that needs to be changed to a rational, scientific idea of the gene as a sequence. A complete
understanding of the gene concept ideally involves an accommodation of both conceptions. Tsui
and Treagust (2004) concluded that “In case of learning about genes, they [student] have to allow
both the new meaning (processes) and old meaning (matter) to coexist and to access both
meanings depending on context” (p. 200). Based on the ideas about scientific modeling, I
consider students’ alternative conceptions—particle gene and sequence gene—as mental models
resulting from the use of multiple scientific models of genes. With this in mind, an integrated
knowledge of the gene concept will occur when learners conceive multiple models coexisting in
their conceptual ecology and understand that those models’ functions are appropriate in a
particular context.
Moreover, the conceptual change theory generally places emphasis on individual learning
in which students construct mental representations within their own minds (Chi, 1992; Hewson
& Thorley, 1989; Linder, 1993). Social-constructivism objects that a conceptual change
approach ignores the connection between individual and social aspects of learning and between
the classroom and the outside world (Cobern, 1996). Within a modeling framework, a conceptual
model that students learn in the classroom is a collective product that is socially constructed from
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scientific community and transferred to the classroom. A student learns about models by
interacting and sharing ideas with teachers and other students. Hence, this framework also allows
us to explain student learning in relation to scientific practice at large and social construction of
knowledge in the classroom.
Multiple Models of the Gene
Throughout the history of biological research, multiple scientific models of genes have
been developed in an attempt to fully understand and explain particular facets of genetic
phenomena (Portin, 2002). One model alone does not necessarily account for all explanations of
data; collectively, multiple models may be able to provide a more complete understanding.
Rheinberger and Müller-Wille (2010) observed that “More than a hundred years of genetic
research have rather resulted in the proliferation of a variety of gene concepts, which sometimes
complement, sometimes contradict each other” (Rheinberger & Müller-Wille, 2010). Some
philosophers and scientists have attempted to reach a consensus on a definition of the gene by
consolidating the variety of gene models, while others take a pluralist stance, accepting multiple
gene models (concepts)4 based on the development of scientific practice and the function of
models (Moss, 2001, 2004; Portin, 2002; Rheinberger & Müller-Wille, 2010).
The philosophers explored the historical development of the gene concept in biological
research. Portin (2002) categorized concepts of the gene as: the classical concept of the gene, the
neoclassical concept of the gene, and the new concept of genes that does not fit into the classical
or neoclassical criteria. Rheinberger and Müller-Wille (2010) reviewed gene concepts in
classical genetics, molecular genetics, and evolution and development.
4 Note the literature from education research area mostly use ‘model’ and those from philosophy of science area use ‘concept’. I believed both convey the same meaning; however, in order to maintain linguistic accuracy I applied words pertaining to the papers.
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Other researchers studied various versions of the gene presented in textbooks in order to
trace the development of genetics. The version of scientific models used in high school curricula
and instruction can be seen as a simplification of scientific models in practice (Gilbert & Boulter,
2000). Gericke and Hagberg (2006, 2009, 2010) identified five historical models of genes: the
Mendelian model, the classical model, the biochemical-classical model, the neoclassical model,
and the modern model. In addition, Flodin (2009) described five different gene concepts used in
college biology textbooks: the gene as a trait, an information-structure, an actor, a regulator, and
a marker. Interestingly, Stewart, Cartier, and Passmore (2005) proposed three interrelated genetic
models addressed in genetics literacy: (a) a genetic model describing patterns of genetic
inheritance; (b) a meiotic model describing segregations of genes at the chromosomal and
cellular level; (c) a molecular model describing mechanisms that link genotypes to phenotypes.
This paper focuses on gene models that are represented in high school curricula. In
general, high school genetics curricula could be delineated into two main areas: classical
genetics, which focuses on genetic inheritance and Mendel’s laws; and molecular genetics,
which focuses on molecular processes of genetic phenomena, such as the structure of genetic
materials, DNA replication, and protein synthesis. Molecular genetics complements the
explanation provided in classical genetics by placing emphasis on cellular and molecular
mechanisms (Waters, 2004). For this reason, I propose two different ways to conceptualize
genes: the classical model and the molecular model.
• The classical model represents the gene as a particle that controls genetic traits
transferred from parents to offspring.
• The molecular model represents the gene as a sequence of instructions that are
expressed to control the structure and function of the cell.
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The historical roots of the classical and molecular models. Our understanding of
genetics began in 1866 with the work of Gregor Mendel on genetic inheritance. Mendel
introduced a tool for an analysis of patterns of inheritance, and on this account he believed that
observed traits were related by ‘factors’ that are now termed ‘genes’ (Flodin, 2009). The term
‘gene’ was later coined by Wilhelm Johannsen in 1909 (Portin, 2002). During the early 20th
century, scientists comprehended the gene as a hypothetical unit of inheritance, without
connection to physical objects (Rheinberger & Müller-Wille, 2010). Thus, genes were identified
through observable phenotype differences such as a gene for seed shape, a gene for hair color, or
a gene for cystic fibrosis. In the classical gene model, genes are essentially symbols that explain
how genetic traits are transferred to next generations on the basis of mathematical probabilities.
For example, students are introduced to symbols representing alternative versions of genes such
as dominant allele ‘A’ and recessive allele ‘a’ and lean to predict the patterns and probability of
genotypes/phenotypes.
By the 1940s, geneticists discovered that genes are located on chromosomes and the
behavior of chromosomes during meiosis account for inheritance patterns. At this time the gene
became less hypothetical and began to change from an abstract genetic unit to a discrete material
entity (Falk, 2000; Rheinberger & Müller-Wille, 2010). Another representation of the classical
gene model developed during this time was a highlighted section of chromosomes depicting the
locus of genes on chromosomes or a segregation of genes at the cellular levels—this model is
called a meiotic model (Stewart et al., 2005). The analysis of my study will place less emphasis
on the meiotic model, because the classical and meiotic models correspondingly function in
investigating genetic inheritance and they are often presented in the same unit in high school
curricula.
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The classical model is constructed to investigate patterns of genetic inheritance; the
model therefore guides and constrains classical geneticists to investigate certain kinds of
questions such as the probability of genetic diseases and population genetics. Soon scientists
began to gain interest in questions about the entity of genetic materials and mechanisms of how
genetic material determines genetic traits and biological function in the body. Henceforth, a new
model was needed.
The breakdown of classical genetics began when the nature of the genetic material
became more accurate with the advancement of technology for biological research (Rheinberger
& Müller-Wille, 2010). During the middle of the 20th century, scientists discovered the physical
and chemical structure of genetic material, understood how a gene functions to control a trait,
and cracked the genetic code that encoded genetic information (Portin, 2002). With the
knowledge about the DNA model and gene expression processes, scientists learned that
sequences of nucleotides contain genetic information inherited from parents and coded for
proteins in order to direct the development and function of organisms. Thus, based on new
information, the notion of the gene evolved into what is known as the molecular gene model.
In the molecular gene model, the focus of the gene is shifted from physical particles to
sequences of instructions. The gene is conceptualized as information, instruction, code, or data
in the genome that synthesizes proteins in order to regulate cellular processes (Waters, 2008). A
representation of the molecular gene model is depicted in the symbolic mode as sequences of
information such as a nucleotide sequence 5’ ATGCTTACTGG 3’. For example, students learn
that a change in a DNA sequence (mutation) may cause a changed or malfunctioning protein that
could result in a genetic disease.
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This new gene model explains genetic phenomena at different biological levels and in
different explanatory contexts. With the molecular gene model scientists discovered the
mechanism of DNA replication, which expands our knowledge from using the classical model
about genetic inheritance to the molecular level. Scientists have applied the molecular model to
reveal the processes of gene expression. Moreover, this model permits scientists to investigate
new questions, such as the influence of environmental factors on genetics, which were
unexplained by the classical model alone.
With the advent of technology in science, new biological technologies have arisen, such
as DNA sequencing, Polymerase Chain Reaction (PCR), and cloning. The breakthrough of
genetic engineering has made it possible to isolate, clone, and modify genes in order to control
and manipulate gene expression of organisms. Moreover, the molecular gene model explains the
underlying knowledge of current genetics and technology. The molecular gene model is,
therefore, an essential concept that students must grasp in order to meaningfully understand
current genetics and other biological fields.
It is important to note that this paper does not suggest that learning classical genetics is
no longer important. In a classical genetics unit, students learn basic concepts of heredity, which
are essential for them to understand how genetic traits are inherited generationally. Additionally,
genetic inheritance is relevant to personal experience, cultural experience as well as everyday
discourse (Condit, 2010b), providing an important beginning point for students to make
connections from daily life to the science classroom. For example, students know that a child
inherits the dark hair trait from his parents or that the blue eye trait runs in his family.
Furthermore, scientists still use the classical model in conducting genetics related research. In
conclusion, the two models have different structures, functions, representations, explanatory
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domains, and applications, which make both models as equally valuable tools for investigating
genetic problems (see Table 5).
Table 5
Description of Different Characteristics of Gene Models.
Characteristics Classical gene model Molecular gene model
Structure Allele/part of chromosome Nucleic acid sequence
Function Controlling a phenotype Coding information for a protein
Conception Passive/Active particle Sequence of instructions
Symbolic representation Aa/AA/aa AATCGTCA
Biological level Cell/Organism/Population Molecular
Explanatory domain Pattern of genetic inheritance Gene expression, Mutation
Application Classical genetics, Population genetics Molecular biology, DNA technology
The discussion on coexisting gene models in genetics. The science of molecular
genetics has advanced and to some extent overshadowed the application of studies in classical
genetics. For example, Mendal observed dominant/recessive relationships of alleles, but the
patterns of inheritance of most traits could not be quantitatively predicted based on
oversimplified clear-cut phenotypic differences. In order to explain natural variation of traits,
scientists have applied molecular genetics knowledge to determine mutations in genomes and to
explain interactions between genes and environments. Although some ideas from classical
genetics have been supplanted by the mechanistic understanding brought by molecular
discoveries, many remain intact and in use. Examples of current applications of classical genetics
include such things as plant breeding improvement, prediction of inherited disorders, and genetic
counseling. Population genetics also uses the term gene, in most instances, as a static unit of
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calculation for finding the frequency of certain genes in order to identify different properties
within a population (Portin, 2002).
Philosophers have raised the controversial question of whether classical genetics has been
or will be replaced by molecular genetics. Reviewing this issue helps us understand the
importance of both models in high school science curricula and how the classical and the
molecular model are associated. This review is mainly based on a thorough philosophical
analysis by Waters (2008).
According to Waters (2008), Schaffner (1969) hypothesized that the science of classical
genetics was theoretically reduced to molecular genetics, based on the reductionism theory by
Nagel (1961). However, the anti-reductionism camp argued that classical genetics was and
would not be reduced to molecular genetics. Hull (1974) explained that the fundamental terms of
classical genetics could not be suitably translated to terms in molecular genetics. Kitcher (1984,
1999, 2001) proposed that classical genetics explained the transmission of genetic traits rather
than the development of traits in individual organisms explained by molecular genetics. To
illustrate, the explanation of two models focuses on different explanatory domains. Kitcher also
pointed out that genetic inheritance is best explained at the level of cytology, rather than at the
molecular level. Rosenberg (1985) stated that there is no manageable connection between a
classical gene identified by phenotype and a molecular gene identified by sequences.
However, another camp opposed the claims of anti-reductionism, countering that the
assumption regarding classical genetics was only partially correct (see Sarkar, 1992, 1998;
Schaffner, 1993; Waters, 2008). They argued that classical genetics implies a complex
relationship between a gene and a phenotype, not merely a simple one-to-one relationship as
claimed by anti-reductionists. Furthermore, Waters (2008) critiqued Kitcher’s idea, arguing that
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in fact molecular genetics could also explain the transmission of genes. Conversely, Vance
(1996) shifted the focus of the debate from theory to investigative practice. Vance concluded that
contemporary genetics depends on the methods and knowledge of classical genetics; as a result,
classical genetics is not reduced to molecular genetics.
The debate over the reductionism of classical genetics to molecular genetics has not
concluded. In this post-genomic era, the gene concept has become even less defined; not simply
as one gene for one protein. The common ground between the classical and the molecular gene
models becomes harder to demarcate. Regardless of the philosophical debate, in practice
scientists continue to use both sets of tools to explain genetics phenomena.
For the purposes of understanding high school genetics, the coexistence of the two
models could be explained based on scientific modeling theory. Since the investigation of
complex objects such as biological phenomena entails different domains, each domain is best
explained at a particular level of theoretical discourse. A model focuses only on specific aspects
of the phenomenon, rather than on every aspect of a phenomenon (Ingham & Gilbert, 1991).
Thus, the power of a particular model for explaining the natural phenomena is limited. As
Cartier, Rudolph, and Stewart (2001) stated:
Once constructed, models influence and constrain the kinds of questions scientists
ask about the natural world and the types of evidence they seek in support of
particular arguments. They guide a researcher’s perception of what is involved in
the natural processes of the world. (p. 5)
Furthermore, a community of scientists continuously assesses the value of different
models based on their potential to explain data and predict the results of observation and whether
they are consistent with other ideas (Gilbert & Boulter, 2000). A proposed model may no longer
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have the power to explain emerging scientific questions; in order to probe new phenomena and
collect additional data, a new model might be constructed. The complexity of models is therefore
refined overtime (Gilbert, 2005).
Since the nature of a model is limited to depicting only particular aspects of reality,
multiple models of the same phenomenon could be produced according to the development of
science. Multiple models could be essentially different in terms of functions, levels, or domains
in explaining phenomena; the difference between models exceeds the difference between their
respective components. Halloun (2007) explained that multiple models are used to explain
complex phenomena and those models cannot replace one another:
Two scientific models may represent the same pattern without having one model
completely reducible into the other. However, the two models may not then
belong to the same scientific theory, and they cannot allow us look at the pattern
from the same perspective. (p. 43)
A variety of gene models, each with particular domains of application, can have more
explanatory and heuristic power than one universal model definition of genes (Sterelny &
Griffiths, 1999). Waters (2008) concluded that:
Hence, the ideal structure for biology is akin to a layer-cake, with tiers of theories,
each of which provides the best possible account of its domain of phenomena.
Biological sciences such as classical genetics that are couched in terms of higher
levels of organization should persist, secure from the reductive grasp of molecular
science, because their central theories (or patterns of reasoning) explain domains
of phenomena that are best explained at levels higher than the molecular level.
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This discussion informs us that both classical and molecular gene models are powerful
tools that currently persist in biology; however, they are used separately in specific domains.
According to Flodin (2009), different practices create different discourses leading to different
ways of talking about and referring to genes. The meanings of the gene, therefore, are tied to the
particular scientific discourses and variations of the gene concept are used in different sub-
disciplines in biology. Accordingly, the classical model is still applicable for explaining genetic
transmission. The more recent conception of the gene has never completely replaced earlier
explanations in classical genetics, and multiple scientific models of genes coexist together to
explain complex phenomena (Morange, 2005).
The Analysis of the Gene Concept in the Science Curriculum
To inquire into the lack of understanding about the gene among students reviewed in the
previous section, I analyzed how multiple models of the gene are represented in the biology
curricula (see Table 6). As a case study of genetics curricula in Thai high school genetics, I
sampled representations related to genetics from a Thai biology textbook (IPST, 2005) and a
Campbell biology textbook (Reece & Campbell, 2011). Sample pictures related to phenotypes,
the classical gene model, and molecular gene model were selected from classical genetics,
molecular genetics, population genetics, and DNA technology units in each text. The selection
was intended to cover a variety of representations of models, modes of representation, and
connections found in the two texts. The left column of the table shows multiple representations
of phenotype and genes from either the classical model or molecular model categories. The
column on the right contains representations with the connection between gene models and
phenotype.
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Table 6
Examples of Representations Depicting the Classical Gene Model, the Molecular Gene Model and Phenotype.
Pictures Pictures with connections Phenotype
Classical model and phenotype
Classical Model
Classical model, Meiotic model, and phenotype
Molecular Model Molecular model and phenotype
1A 2A 3B
4B 5B
6A
7A 8A
9A
10B
11A 12B
13B 14B
15B 16A
17A
Note. Pictures are selected from IPST’s Thai textbook and Campbell’s textbook to illustrate a separation of multiple models of genes into different domains of application and a disconnection between genes and phenotypes. Pictures labeled with A are from IPST’s Thai textbook (IPST, 2005) and pictures labeled with B are from Campbell’s textbook (Reece & Campbell, 2011).
7A
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In general, the textbook analysis showed that the gene concept in high school curricula
has followed the historical development of the gene concept in genetic research. The current
Thai biology textbook presents classical genetics followed by molecular genetics, discretely into
two units. The gene models are represented in a linear fashion from the classical model to the
molecular model without describing the connections or the ongoing simultaneous use of both
models in scientific practices. My initial hypothesis for why students did not develop a basic
knowledge of the molecular model after instruction was that the current teaching or textbooks
might place less emphasis on the molecular model. On the contrary, the analysis revealed that the
molecular model is presented in current instruction and students are encouraged to use it to solve
problems. Indeed, the main reason why students had incomplete understanding of genetics is that
current curricula present the molecular model disconnected from the classical model in two
specific explanatory domains, as discussed in a ‘missing links between the gene models’ section.
Based on the textbook analysis, three main factors that could lead to a difficulty in
learning genetics are: a) the abstract gene concept, b) hidden pathway from genes to phenotypes,
c) and missing links between the gene models.
The abstract gene concept. First, the analysis of textbooks revealed that genes are
repeatedly represented in an abstract way, detached from genetic materials or from genetic traits.
The idea of the gene is first introduced to students as a hypothetical unit, not as a physical object
of genetic material. Rather, genes are identified by observed phenotype differences. This idea
about classical model as a hypothetical unit is presented in the same fashion with the previous
review of how conceptualized the gene to solve problems in classical genetics.
In addition, textbooks use various modes of representation identified by Gilbert (2005)
(including verbal mode, symbolic mode, visual mode) to represent phenotype and genes. To
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learn genetic phenomena, students have to make sense of these multiple representations. The
common representations that students use to solve genetics problems in the classroom are in a
symbolic mode (4B in classical genetics and 6A in molecular genetics). These symbolic
representations mostly have no explicit connection to organisms or to concrete genetic material.
In particular, students calculate the probability of genotype or translate sequences without
thinking about organisms and related biological processes. An exclusively abstract understanding
of the gene model may lead to a difficulty in learning genetics.
Hidden pathways from genes to phenotype. It has been documented that students
could not draw connections among genes, phenotype, and genetic phenomena (Duncan, 2007).
The textbook analysis therefore focuses on how representations in the textbooks show the
connection between phenotype and genes. The results showed that in classical genetics and
population genetics there are many instances of the connection between the classical model and
phenotype (such as 11A to 14B). Students learn about genetic inheritance in real contexts by
associating the classical gene to the concrete phenotype and organisms.
However, in molecular genetics, representations with connections between molecular
models and phenotype were rarely found. Molecular genetics instruction is often taught and
represented in textbooks in a manner that isolates the molecular processes from the organism in
which the biological processes actually take place. Unlike representations in classical genetics,
most representations focus only on mechanisms at the molecular level without reference to any
phenotypes or organisms. A clear picture is not establish of relationships among different
domains such as genes, proteins, cells, and phenotypes related to genetic phenomena (Duncan &
Reiser, 2007). The role of proteins in biological pathways to phenotype is omitted from high
school curricula.
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The molecular model provides an explanation of how a gene brings to expressed
phenotype which the limited classical model could not explain. In other words, students need the
link between an information level (e.g. genetic information, sequences of nucleotides) and a
physical level (e.g. genetic material, chromosome, DNA) (Roseman, J. E., Caldwell, A., Gogos,
A., & Kurth, n.d.). Applying genetic information in the real-world context, the selected picture
17A is a powerful tool to help students establish connections between genetic material and the
expression of genes to phenotypes. A complete understanding of the molecular gene and
phenotypes could potentially guard against a genetic deterministic view and the conception of
genes as actual traits.
Missing links between the gene models. The results revealed that the gene concept is
presented in an inconsistent way, as there are multiple distinct models of genes presented in the
science textbooks. The textbook analysis showed that historically different models of genes are
presented separately in different explanatory domains and are explained with different forms of
reasoning. The applications of these models are independent, as argued by anti-reductionism
group. Classical models are found in the genetic inheritance unit (4B, 5B, 11A -13B) and
population genetics unit (14B). The classical model is used for explaining genetic transmission
across generations and calculating the probability of an individual inheriting a gene. On the other
hand, molecular models appeared only in the molecular genetics units (6A, 7A, and 8A) and the
DNA technology units (9A and 10B). The molecular model in the textbooks is used to explain
DNA replication, protein synthesis, mutation, DNA synthesis, and cloning; the explanation
focuses on the molecular level of an individual. The findings confirm that models of genes are
often presented separately and used in different sub-disciplines or contexts, but not discussed
together (Albuquerque, 2008; Gericke & Hagberg, 2006, 2010). One explanation is that the gene
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models were initially developed to answer different questions about genetic phenomena; hence,
the applications of those models are naturally in different domains.
Notably, the analysis showed theoretical inconsistency of the gene concept, multiple
conceptions and changes in its meaning could lead to confusion in learning genetics. Since each
gene model is used for particular purposes and presented in different forms, the explicit
connection between them is never presented. This problem leads to the omission of underlying
phenomena and confusion when learning genetics. Before the discussion of the link between
classical and molecular models, I will discuss an example of missing links between the classical
and meiotic models.
Classical model and Meiotic model. The research has shown that students encounter
problems because of missing links between the classical and meiotic models (Stewart, Hafner, &
Dale, 1990; Stewart & Van Kirk, 1990). While students were able to solve genetics problems
using algorithms and calculate probability using Punnet squares, some students did not
understand the underlying genetics concepts nor were they able to explain the phenomena with
the cell division (Kindfield, 1992). With the classical model, student explanations focused on the
patterns of inheritance through transmitting symbolic alleles over generations. With the meiotic
model, student explanations focused on segregation of genes located on chromosomes at the
cellular level. Students generally learned about segregation after the patterns of inheritance, and
they are expected to make their own connections between the classical and meiotic models. With
these theoretical differences, students however could not make connections between the two
models. Similarly, Lewis and Wood-Robinson (2000) gathered and reported evidence that
students were not aware of the relationship among alleles, genes, and chromosomes.
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The research suggests that bridging multiple models in an explicit manner can help
students understand the underlying explanation of genetic phenomena as a connected big picture
(Stewart et al., 1990; Stewart & Rudolph, 2001; Stewart & Van Kirk, 1990). Some connections
are made between the classical and meiotic models in current textbooks, such as illustrations of
the segregation of a classical gene on chromosomes during cell division (15B and 16A). Another
method that might enhance connection building and assist students in solving genetics problems
is the use of a multiple-linked representation of genes and chromosomes in the Punnet square.
Instead of using only alleles/genotypes in the representation, the inclusion of the drawing of
chromosomes helps students associate probability calculation with actual cell division processes.
Classical model and Molecular model. A change in theoretical meaning between
classical and molecular models is even larger. Both the classical and meiotic models are applied
to explain genetic phenomena within the same context about genetic inheritance; however, the
molecular model is used in different domains of application. Interestingly, the analysis revealed
that no single place in the textbooks draws the connection between the classical and molecular
model. Although both refer to the gene, each is taught as a completely separate idea. The
classical and the molecular models represent the gene as, respectively, a particle and a sequence
of instruction.
In the classical genetics unit, teachers generally teach genetic inheritance in terms of the
transmission of genes as particles on chromosomes, but most teachers do not connect this genetic
process to the transmission of genetic information. In the molecular genetics unit, students may
begin with a lesson on the discovery of genetic material and then learn about DNA sequences
and gene expression. However, explicit connections between classical and molecular models are
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not made. As a result of this missing link, students may not see a connection between genetic
inheritance and the function of the body.
One may object that an understanding of genetic information or the role of proteins is not
necessary for reasoning about genetic inheritance in classical genetics and that students will
eventually learn about this content in a molecular genetics unit. However, evidence shows that,
with the way genetics is currently taught, most students conceptualized genes as particles, even
after they finished their molecular genetics lessons. The classical model limits students’ ability to
provide causal explanations of genetics phenomena, because they make a direct link between the
gene and the trait without requiring an intermediate mechanism (Duncan & Reiser, 2007). When
students view genes as sequences of instructions, they are able to draw connections to the protein
and RNA strand. Therefore, they conceive genetic phenomena as complex processes related to
other biological phenomena in a biological pathway.
To demonstrate, students are not taught how genotype AA or allele A from classical
genetics connects to the gene sequence for producing proteins from molecular genetics. Redfield
(2012) claimed that “Most students mistakenly believe that alleles are intrinsically either
dominant or recessive, as did Mendel” (p. 2). Students leave class deeply confused about the
meaning of dominance— that the dominant allele is a nucleotide sequence coded as a
functioning protein so that a phenotype is expressed according to the dominant allele. The
molecular process underlying the meaning of dominance is neglected.
The genetics curriculum fails to provide bridges for students to make connections
between classical and molecular genetics; the molecular gene model is not presented in classical
genetics and vice versa. In other instances, students are expected to be able to independently
build bridges between those models and apply them meaningfully. One may argue that scientists
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use multiple gene models interchangeably and that they are able to make the connections
between these conceptual differences in their minds. However, educational research has shown
that making such connections is not the case for high school students. Unlike scientists who are
considered experts, students as novices are unlikely to comprehend all concepts in a coherent
way. Therefore, without explicit connections connecting the two scientific models, or even the
acknowledgement of the multiple models of the gene in the science curriculum, students are
unlikely to develop meaningful understandings of the nature of the gene in the way we would
envision them as needing.
To sum up, this suggests the difficulty of teaching the sequence of instruction model as
alternative to the particle model. Instead, we should teach it as compatible with the particle
model. The challenges students face in learning about genetics are: a) to make sense of multiple
models of the gene, especially the molecular model and b) to apply appropriate models to solve
problems related to genetic phenomena. I argued that missing links between the two models in
high school genetics curricula lead to a lack of complete understanding of genetics. Without the
connection, only the classical gene model becomes dominant in students’ minds, and they may
not develop or apply the complex molecular model in explaining genetic phenomena. As Stewart
et al (2005) pointed out an understanding of genetics is the understanding of the interrelated
models of genes: not only understanding the separate models, but also integrating them to
generate coherent and comprehensive explanations of genetic phenomena. To explain genetic
phenomena, students therefore need to be able to comprehend both the classical and molecular
models in complementarity.
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Discussion
Knowledge of current genetics is an important foundation for students in learning biology
and DNA technology in the bioinformatics era. This chapter tackles the conceptual difficulties of
learning genetics, particularly the concept of the gene. Research has shown that most students do
not conceptualize the molecular gene model that is applied in genetics as we understand it today.
I argue that the problem of difficulty in learning current genetics is not because we do not teach
students about current genetics, but rather because we do not have the full picture of what we
actually teach. Current genetics curricula leave unconnected numerous pieces of information,
which hinders student understanding of genetics.
The reviewed literature revealed that the gene concept has been developed continuously
throughout the history of genetics; and the nature of the gene concept is intangible, complex, and
incoherent. Multiple models of genes are used in high school curricula, but the textbooks do not
address the coexistence of these models. The classical and molecular models have incompatible
meanings in terms of structures, functions, levels, contexts, and application. Students are
expected to develop an understanding of genetics topics through interpreting, constructing, and
linking various representations of both the classical and molecular gene models. The multiple
models, if not taught explicitly, may make it difficult for students or even teachers to
comprehend genetics. Teachers oftentimes teach by following a sequence of content presented in
the textbooks. However, the analysis showed that classical and molecular models are presented
separately without any connections in the textbooks. The classical gene concept therefore
becomes dominant in students’ mind due to imbalanced curricula and students do not apply the
molecular model when reasoning about genetic phenomena.
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Since both the classical and molecular models are scientifically important tools for
answering certain kinds of genetic problems, it is important for students to understand both
models. Furthermore, students should be able to make connections between the two models,
move flexibly between different models, and apply appropriate models to solve the problems. To
support students in developing an up-to-date understanding of the gene, a gap needs to be
merged between the classical model of the gene as a particle in Mendelian genetics and the
molecular model of the gene as a sequence of instructions in molecular genetics. An example of
a connection between the models that students should be able to make might be structural
connections from a sequence of nucleotides at the molecular level, to a DNA double helix, to a
section on a chromosome, and to an assigned allele. In addition, students should be able to
explain a genetic phenomenon based on the complementarity of both models as previously
shown in the example.
We need to redesign current genetics curricula and develop a teaching pedagogy to
bridge conceptual divisions between multiple models. Condit (1999) claimed that the structure of
the genetics curriculum should be reorganized by placing the emphasis on the molecular model,
because it provides the foundation for understanding abstract concepts manifested in the classical
model. Such dramatic reframing would require intensive efforts; in addition, students would have
to begin with the more complex cellular and molecular mechanisms. I proposed that the
molecular model rather should be gradually introduced in connection with the classical model
through the aid of multiple-linked representations (Kozma, 2003).
Presenting both models in connection with multiple-linked representations could help
students establish the structural connection they are missing when these are kept separate. The
designed learning materials with multiple-linked representations should engage students in a
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discussion of how a sequence of instructions correlates with the symbolic model of alleles and
genotype. Providing students opportunities to work with the models and engage in authentic
problems could help them develop understanding by applying the models within phenomena.
Solving genetics problems by using multiple models of genes could reinforce connections
between gene models and genetic phenomena and create awareness of the significance and
limitations of gene models.
To address this issue in the real classroom, future research needs to study all aspects to
inform the development of genetics education from students’ learning, curriculum design,
teachers’ knowledge and pedagogy, and interactions in the classroom. The curriculum is
mediated by teachers and others and it is situated within complex learning/schooling
environments. A teacher makes the cultural tools of science (like scientific models) available to
learners and supports their (re)construction of the ideas through discourse. It is important for
teachers to acknowledge the existence of multiple models of genes and students’ difficulties in
constructing a coherent idea of the gene. Students should be provided with ample opportunities
to explore and apply models in the classroom. The redesigned curriculum could enhance
students’ reasoning, their ability to construct and use models, and ultimately assist in increasing
meaningful understanding of genetics.
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CHAPTER 3: Methodology
Introduction to the Chapter
The over-arching goal of this research is to gather information about the teaching and
learning of genetics that supports the development of a set of principles for teaching multiple
scientific models. This research focuses on five aspects of specific problems regarding
challenges in teaching and learning multiple models of the gene embodied in current high school
curricula. Chapter 3 discusses the research methods for exploring the questions framed in the
previous chapters:
1. What are teachers’ content knowledge and pedagogical content knowledge about the
multiple models of the gene?
2. What are effective pedagogical strategies for teaching multiple models of the gene
with the goal of achieving coherent, integrated, and meaningful understanding?
3. How do the learning materials created in this design-based research project impact
students’ understanding of multiple models of the gene?
4. What are the factors that influence the implementation of the designed learning
material in Thai classrooms?
This chapter provides a description of a) research design, b) recruitment and sample, c)
data collection, and d) data analysis. Given the complex nature of these questions, a comparative
case study using qualitative methods was chosen as the appropriate research design for
investigating teachers’ pedagogical content knowledge in teaching genetics, students’
understanding of multiple models of gene, and the implications of the designed learning material.
The present study, which synthesizes disparate types of data collected over time as
teachers engaged in interviews, group discourse, surveys, and classroom observations, marks the
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initial iteration in refining principles for the design of learning materials in order to set the stage
for future studies.
Research Design
The methodological approach of this study is based on design-based research. Design-
based research is an approach for studying learning in context as well as the intervention or
environment that can be designed to support such learning (Brown, 1992; Cobb, Confrey,
DiSessa, Lehrer, & Schauble, 2003; Allan Collins, 1992). As a formative research strategy, the
design-based research approach aims to engineer a particular form of learning while
systematically advancing the development of specific learning theories (Cobb et al., 2003; Allan
Collins, Joseph, & Bielaczyc, 2004; Kelly, Lesh, & Baek, 2008). In design-based research
studies, “What works is underpinned by a concern for how, when, and why it works, and by a
detailed specification of what, exactly, it is” (Cobb et al., 2003, p. 13).
One defining feature of design-based research is that it addresses theoretical questions
about the nature of learning within an authentic setting. Instructional design is viewed as an
integrated system addressing multiple educational elements such as curriculum, assessments,
roles of students and teachers, roles of technology, and professional development (Brown &
Campione, 1994; Brown, 1992). Design-based research, therefore, provides a better
understanding of a learning ecology—a complex interacting system involving multiple elements
affecting learning—by designing its elements and by anticipating how these elements function
together to support learning (Cobb et al., 2003). In addition to evaluating intervention outcomes,
this method allows researchers to explore pragmatic aspects of practice in order to inform the
customization of interventions (Linn, Davis, & Bell, 2004; The Design-Based Research
Collective, 2003).
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As is the characteristic of design-based research, the goal of this study is to investigate
learning and teaching about multiple scientific models and to explore the implementation of
designed learning materials within an authentic learning context. The learning materials were
grounded in principles from research on multiple-linked representations. The choice of design-
based research for this study is appropriate because it allows us to test and refine principles for
teaching the gene concept, as well as to investigate the effects of designed learning materials
across multiple settings. Thus, while developing and evaluating new learning materials, I was
also able to explore concerns about teaching practice and relevant theoretical variables,
particularly those related to Thai high school classroom.
The design process is both prospective and reflective (Cobb et al., 2003). On the
prospective side, designs are implemented with a hypothesized learning process and the means of
supporting it in advance, which are built around a well-theorized set of design principles. In this
research, instructional designed are guided by principles from the literature on multiple-linked
representation and the scientific model (reviewed in chapter 1 and chapter 5). On the reflective
side, design-based research is a series of conjecture-driven tests with several levels of analysis.
In other words, researchers need to constantly evaluate the outcome of instructional designs
based on the framework, and continuously revise the design based on the evaluation in a
systematic way. Consequently, one salient feature of design-based research is an iterative design
process featuring cycles of invention and revision (Cobb, 2001; Allan Collins, 1992). This
research therefore was conducted in continuous cycles of design, enactment, analysis, and
redesign.
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This study was divided into three phases: Pilot study, Development, and Implementation,
with data collection and analysis for each phase building on the previous phase’s work (see
Figure 6). Through this design process, the principles for teaching the gene concept as well as the
learning materials were continuously developed and modified based on teacher comments and
implementation in the classroom. The intervention implementation was conducted at the final
round; further redesign and implementation are anticipated in future studies. The main aim of
this work was to identify principles for facilitating students’ understanding of genes that other
teachers can use for planning their teaching. Thanks to the progressive refinement in design, this
research could lead to sharable theories that directly inform relevant educational practices.
Figure 6. Research design and data collection in three phases
Pilot Study
Phase I (Oct’11)
Development
Phase II (Dec’11)
Implementation
Phase III (May-Aug’12)
United States
3 teachers
Rawai city, Thailand
6 teachers
Survey
Group Discussion
Survey
Group Discussion
Teacher Interviews
Ban Chang city, Thailand
5 teachers & 1 control case
Survey
Discussions on the tools
Teacher Interview
Classroom Observations
Student Interviews
Fellow-up Interviews
Rawai city, Thailand
2 selected teachers from Phase II
Classroom Observations
Student Interviews
Fellow-up Interviews
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Phase I: Pilot study. The purposes of the pilot study were to explore initial ideas about
teaching strategies for connecting multiple models, define the design process for developing
learning materials, and develop data collection protocols. The study site of this phase was in
Midwestern United States. Since the pilot study was situated in a different institutional and
cultural context from the main study situated in Thai education, the data from this phase is
treated as one case separated from the comparative case study of Thai participants.
High school teachers who had experience teaching genetics topic were recruited;
participants were identified with the help of teachers affiliated with the Science Education
research group at the university. Three teachers voluntarily participated in the research by
attending a discussion group. The participants included two female teachers of agricultural
science and one male retired teacher who had taught high school genetics. The retired teacher
was also involved in projects for science learning materials development at the time of this study.
The participants engaged in one four-hour group discussion that addressed topics related
to students’ conception of genes, multiple gene models, and instructional strategy. Discussion
questions were designed to document participants’ teaching experience, subject matter
knowledge, and pedagogical content knowledge about genetics. The group discussion was
videotaped and audiotaped with the permission of participating teachers. Following the
discussion, the learning materials were modified according to teachers’ comments and
suggestions. Participants also completed a 20-minute survey about their educational background
and background in teaching genetics. A revised version of agenda, discussion questions, and
survey exploited in next phases are presented in the Appendix.
Although the development phase and the implementation phase were situated in the Thai
education system, many previous studies have shown that the problem concerning students’
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understanding of genes is found across countries—the United States, England, Australia,
Germany, and Turkey (Franke & Bogner, 2011; Saka, Cerrah, Akdeniz, & Ayas, 2006; C. Tsui
& Treagust, 2004; Venville & Treagust, 1998). In order to account for the contextual differences
between the Thai and American educational systems, in phase II and phase III I collaborated
with Thai teacher participants to adapt the tools to the Thai context. For example, genetic traits in
the problem should be common in Thailand or familiar to Thai teachers and students.
Phase II: Development. Both phase II and phase III were carried out in Thailand. For
this purpose, data collection tools, learning materials, and group discussion structure from phase
I were amended and translated into Thai. The main objective of the development phase was to
continuously modify the design of teaching tools and to readjust them to the Thai educational
context. Another purpose of this phase was to investigate Thai teachers’ knowledge and
pedagogy regarding genetics topic. To enhance the validity of the research methodology, data
from survey, individual interviews, and group discussion observation were triangulated to
confirm and disconfirm the generated analysis.
Phase II was conducted in Rawai city, an urban area located in the eastern part of
Thailand. Data collection in this phase was conducted over about three weeks during the second
semester5 (December 2011). Six Thai biology teachers agreed to participate in surveys and
individual interviews. Four teachers volunteered to participate in a four-hour group discussion on
teaching and learning high school genetics. During the discussion, I provided multiple
opportunities for teachers to customize the tools. Teachers played an important role by bringing
their ideas and expertise in crafting instructional tools.
5 There are two semesters in the Thai academic year with an optional summer semester. From kindergarten to high school, the
first semester lasts from May until September. The second semester lasts from November until March.
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Phase III: Implementation. The purposes of this phase were: a) to examine teacher
knowledge and pedagogical knowledge about teaching scientific models of genes; b) to further
modify the learning materials for teaching multiple models of genes based on teachers’ ideas and
the emerging ideas from group discussion in the previous phases; c) to explore how teachers
teach the gene concept in classrooms; and d) to investigate student knowledge and their use of
multiple models of genes in solving genetics problem. Data collection in this phase took place
over three months during the first educational semester (May to August 2012).
The first study site was Banchang city, a metropolitan city located in the central part of
Thailand. Six biology teachers who were currently teaching high school genetics were recruited.
Before the intervention, participants were interviewed and engaged in discussions about the
designed learning materials developed in this project. Classroom observations were conducted
with Patcha, Salee, and Wanida to document teaching practice and the implementation of the
intervention (All names are pseudonyms.). After instruction, the teachers participated in the
follow-up interviews to reflect on their teaching practices. Student interviews were conducted to
explore student knowledge about multiple scientific models of genes as well as to reveal the
outcome of implementing the designed tools. In addition to these data sources, I collected lesson
plans, instructional materials, and student work to get a sense of the ways in which gene models
are presented to students. Confirming and disconfirming sampling is a purposeful strategy used
to verify the finding of a study (Creswell, 2012). To compare the effects of the designed tools,
one control case was included in this stage of study. A teacher, Sukan, and her students were also
interviewed with the same protocol used with the intervention group. Classroom observations
were documented. However, the designed tools were not presented to the control case during the
research.
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Due to the low participant response rate in Banchang city, selected teachers in Rawai city
from phase II were also recruited for the implementation phase. Classroom observations, student
interviews, and follow-up interviews were conducted with the volunteered teachers, Kanisha and
Montana. Data collected from these teachers manifested different perspectives, especially on
reforming teaching practice. It is important to note that experience and educational contexts of
this group of teachers were dissimilar to the teachers in Banchang city; for example, preparation
time and familiarity with the learning materials of Rawai teachers were considerably greater.
This issue will be further discussed in the results section.
Recruitment and Sample
Teacher participants. This study is a comparative case study of Thai high school
biology teachers. The teacher participants were selected purposefully with the following criteria.
The first criterion of participant recruitment was science teachers who were currently teaching
high school genetics. Molecular genetics is commonly taught at grade 12 in Thai high schools to
students who are in the science track6. Furthermore, teacher participants were expected to work
collaboratively with the researcher in modifying instructional materials. Since the nature of this
study requires teachers' expertise in order to develop learning materials, the second criterion was
teachers who had taught high school genetics for at least three years. To increase diversity of
teaching experiences among participants, I selected both teachers who had taught biology for
many years and those who were novice teachers. The teaching experience variable was used to
explore whether it influences teachers' knowledge about learning and teaching genetics, and
6 Most Thai high schools apply a tracking system separating students by academic ability and interests into certain classes.
Students in Science track are required to take advance science courses.
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whether it influences their genetics instruction. Equally teacher gender diversity, common school
context, and transportation convenience also informed recruitment decisions.
To recruit teacher participants, I first contacted all biology teachers who teach genetics
from potential high schools in selected area by mail, phone, and in person. A snowball sampling
technique in which existing study subjects refer future subjects from among their acquaintances
was applied to recruiting more participants. School permissions and consent forms were sought.
The small number of participants of each round allowed a possible collaboration with teachers to
develop the learning materials for teaching genetics, along with a rich discussion to elicit
teachers' pedagogical content knowledge. The interview data from the sample size of twelve
teachers would be suitable for a comparison of their knowledge and pedagogy, and the classroom
observations of five teachers would provide in-depth information about their teaching in the real
context. All teacher participants received small monetary incentives for their voluntary
participation.
In phase II, I contacted all public high schools in Rawai city and six selected teachers
from five high schools agreed to participate in the interviews; the rejection rate is 14%. Four
teachers voluntarily participated in the workshop for designing instructional materials: Kanisha,
Montana, Teera, and Atita. Moreover, Kanisha and Montana also participated in phase III for
classroom observation. Recruited participants had various years of experience in teaching
biology ranged from four years to more than 25 years. Teacher backgrounds and school
information are presented in the Table 7; for confidentiality and anonymity of teachers’
participation, pseudonyms were applied.
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Table 7
Teacher Participant Information
Note: IV is a teacher interview, DC is a discussion about learning activity, and OB is classroom observation
Teacher Name Participation High School Name City Gender Age
Years of Teaching
Experience
Teaching Subjects
Educational Degree / Major
Phas
e II
: Dev
elop
men
t TR1 Kanisha IV+DC+OB Montapa high school
Raiwai
Female 26 3-5 Biology Bachelor/Biology TR2 Montana IV+DC+OB Celebrate queen high
school Female 39 10-20
Biology, Science Project Edu. guidance
Master/Biology
TR3 Teera IV+DC Raiwai high school Male 29 3-5 Biology Bachelor/Biology TR4 Malee IV Raiwai high school Female 59 10-20 Biology Bachelor/Biology TR5 Uma IV Academia high school Female 37 5-10 Biology Master/Science TR6 Atita IV+DC Water temple high school Female 57 >20 Biology
Bachelor/Biology
Phas
e II
I: Im
plem
enta
tion TB1 Patcha IV+DC+OB San garden high school
Banchang
Female 57 >20 Biology Master /Biology TB2 Salee IV+DC+OB Deep holy high school Female 43 >20 Biology Master/Sci. Edu. TB3 Wanida IV+DC+OB Park river high school Female 52 >20 Biology Master /Science TB4 Sukan
IV+DC+OB Victory high school
(control case)* Female 59 >20 Biology NA
TB5 Nampen IV+DC College king high school Female 38 10-20 Biology, Middle school Science
Master/Sci. Edu.
TB6 Pakorn IV+DC Lady high school Male 38 >20 Biology
Master/Biology
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Based on the workshop with teachers in phase II, participants illustrated a concern that
lack of experience in creating learning materials had limited their participation in modifying new
learning materials. In phase III, therefore, the target participants were teachers who had
experience in developing learning materials and were from high schools with high level of
academic achievement in science. To recruit participants, I contacted 17 high schools
representing high science achievement guided by the list of top high schools in Thailand in 2011
(http://www.nattapon.com/2011/12/top-100-thai-school/), and six teachers volunteered to
participate in the study. The rejection rate is 65%; the reasons were due to teachers’ busy
schedule, not teaching genetics in the observed semester, and their preparing of students for the
admission exam. Most participants had more than 20 years of teaching experience in science.
Three teachers, Patcha, Salee, and Wanida, voluntarily participated in classroom observations,
and the case of Sukan is treated as a control case. The latter case was recruited from classrooms
that have similar contexts to classroom with intervention (e.g. biology instruction hours, learning
facilities, and the number of students in classes).
Student participants. To explore the effects of the designed instructional materials, after
the instruction, students from the classrooms with the intervention and those from the classroom
without the intervention in phase III were selected to participate in an interview (see Table 8). To
maximize participant variation, the teachers were asked to recruit 18 high school students (n=18)
with diverse genders and levels of science achievement from the classroom with the intervention
(three to five students from each class). Three students (n=3) from the class without the
intervention were also recruited with the teacher’s help. All students participated in the study had
informed consent obtained from their parents/guardians. Names of institutions and individuals
are pseudonyms to preserve anonymity.
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Table 8
Student Participant Information
Student Name Gender School Name City
SRM01 Ananda Male
Montapa high school
Rawai City
SRM02 Bonmee Male SRM03 Tanya Female SRM04 Davis Male SRM05 Ratana Female SRC06 Pornlaka Female
Celebrate Queen high school
SRC07 Sittichok Male SRC08 Nawapon Male SRC09 Anna Female SBS10 Niran Male
San garden high school
Banchang City
SBS11 Chakrit Male SBS12 Jate Male SBD13 Ritda Male
Deep holy high school SBD14 Maha Male SBD15 Piya Male SBP16 Somchai Male
Park River high school SBP17 Vit Male SBP18 Kawin Male SBV19 Yottha Male
Victory high school SBV20 Wally Female SBV21 Panee Female
School settings. This study explored teaching and learning genetics in public high school
system in Thailand. The total of 11 high schools was selected. In this section, some
characteristics of school are described to depict pictures of selected Thai high schools. The study
sites for data collection of phase II and phase III were in different demographic, Rawai city and
Banchange city, respectively. Rawai city, located in the east coast region of Thailand, is a center
for auto and chemical industrials and fishing industry. On the other hands, Banchang is a
metropolitan city located in the Central region of Thailand. The city is an economic center with a
large population. It is perceived that Banchang has higher standards of education than Rawai
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city. Each school had particular structures and educational contexts that shape science learning
and teaching. School sizes, student genders, school types are categorized (see Table 9).
In phase II, the selected schools in Rawai city were all mix genders, except Academia
High School. Sizes of the selected schools were ranged from medium (500-1500 students), large
(1500-2500 students) to extra-large size (>2500 students), according to category by the Office of
The Basic Education Commission (http://www.obec.go.th). Most schools were located in the
urban area. However, Montapa High School was located in a district near the industrial area, and
Celebrate Queen High School was located in the rural area. Raiwai High School is a district
centered school that was large and a magnet school in Raiwai city.
In Banchang city, the selected schools had similar characteristics that they were magnet
schools of Thailand, especially San Garden High School, College King High School, and Lady
High School. Magnet school refers to public high schools that draw students from across districts
with academically selective high schools. Moreover, all selected schools were listed as extra-
large size (>2500 students). It is important to note that all observed schools with the intervention
in Banchang city were male-only schools; however, this was not the research intention. The
common schools in Banchang city were co-ed schools.
Many selected schools, such as Deep Holy High School, Victory High School, and Water
Temple High School, were originated from the Buddhist parochial school, which provided
religious in addition to conventional education. Academia High School was a catholic parochial
school. Historically, schools in Thailand were established in the area of Buddhist temples and
classrooms were taught by monks; these schools were then developed to formal high schools
under the control of the Ministry of Education.
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Table 9
School Information
City School Name Gender Type Size Location
Raw
ai c
ity Montapa HS Mix District centered school Large Urban-Industrial area
Celebrate Queen HS Mix High school Medium Rural Raiwai HS Mix District centered school Extra-large Urban Academia HS Male Parochial school Large Urban Water temple HS Mix High school Large Urban
Ban
chan
g ci
ty San garden HS Male Magnet school Extra-large Urban-historical area
Deep holy HS Male Magnet school Extra-large Urban-historical area Park River HS Male High school Extra-large Urban-economic area Victory HS Mix High school Extra-large Urban College king HS Mix Magnet school/
Demonstration school Extra-large Urban-economic area
Lady HS Female Magnet school Extra-large Urban-historical area
Data Collection
To answer the research questions and validate the findings, multiple sources of data,
ranging from interviews, surveys, focus groups, and observation, were collected. Analyzing
diverse data helped construct a rich map of teaching-learning with multiple scientific models,
which was well aligned the goal of gaining insights into the complex nature of science teaching.
Table 10 shows what data collection method was used to answer each research question. A
questionnaire, an interview protocol, and a discussion guideline were developed over multiple
phases and translated into the Thai language for the main study in Thailand (see the Appendix
for English and Thai versions of data collection tools).
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Table 10
Triangulation Matrix for Research Questions with Multiple Data Collection Methods
Research Questions Data Sources United States Rawai City Banchang City
1. What are teachers’ content knowledge and pedagogical content knowledge about the multiple models of the gene?
Teacher surveys Focus group (n=3)
Teacher surveys (n=6) Teacher interviews (n=6) Focus group (n=4)
Teacher surveys (n=6) Teacher interviews (n=6) Discussions(n=5)
2. What are effective pedagogical strategies for teaching multiple models of the gene with the goal of coherent, integrated, and meaningful understanding?
Focus group (n=3)
Teacher interviews (n=6) Focus group (n=4) Observations (n=2) Follow-up interviews (n=2)
Teacher interviews (n=6) Discussions (n=5) Observations (n=3) Follow-up interviews (n=3)
3. How do the learning materials created in this design-based research project impact student understanding of multiple models of the gene?
Student Interviews (n=9) Observations (n=2)
Student interviews (n=9) Observations (n=3) *Student interviews in the control group (n=3)
4. What are the factors that influence the implementation of the designed learning material in Thai classrooms?
Teacher interviews (n=6) Focus group (n=4) Observations (n=2) Follow-up interviews (n=2)
Teacher interviews (n=6) Discussions (n=5) Observations (n=3) Follow-up interviews (n=3)
Surveys. The purpose of the survey was to document teacher background and their
thoughts about teaching practices. The questionnaire consisted of three sections: a) background
information (such as prior experience and educational background), b) genetics teaching (such as
instructional hours, difficulty in teaching genetics, and teaching materials), and c) teacher
opinions about their pedagogical content knowledge. The 15-minute questionnaire consisting of
questions requiring short responses and multiple choices was administered during the interview.
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Examples of questions in teacher questionnaire:
• What are the textbooks/curriculum/learning kits you use when teaching genetics? (Q.7)
• How much time in the school year do you devote to molecular genetics? (Q.9)
• What do you find to be the most difficult aspect in teaching high school genetics? (Q.10)
• I agree/ disagree that I know enough about genetic inheritance to teach my class. (Q.14)
• I agree/ disagree that I know how to select effective teaching approaches to guide student
thinking and learning in genetics. (Q.16)
Teacher interviews. The purpose of the interview was to explore teachers’ subject
matter knowledge of genes and their pedagogical content knowledge. Six teacher participants
from phase II and six teacher participants from phase III participated in semi-structured
individual interviews that lasted about 45 minutes each. I conducted the interviews in the
participants’ schools approximately two weeks before having the discussions on teaching tools.
The interviews were video-recorded and audio-recorded with permission.
Interview protocol contained questions concerning teachers’ background, teachers’ ideas
about students’ learning, teachers’ ideas about multiple models of genes, teaching pedagogy, and
curriculum and instructional materials in teaching. With the think-aloud approach, teachers
explained the meaning of genes, drew representation of genes, and described the connections
between multiple models of genes. The vignettes about students’ reasoning of genetics using the
particular model were presented to teachers to document their teaching pedagogies. In the last
task, the teachers explained multiple cards of pictures related to genetic materials: a) what are
concepts the representation depict; b) whether and how they used the representation in teaching;
c) how do they see these representations connected. Some pictures were from the textbooks and
some pictures were designed to elicit their ideas about connections between models. The
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interviews generally were guided by the questions listed in the teacher interview protocol and by
derivative questions chosen to clarify or encourage elaboration.
To capture teachers’ knowledge and PCK related to teaching genetics, CoRe (Content
Representations) (Loughran et al., 2006; Loughran, Mulhall, & Berry, 2004) was adapted to
design interview protocol and the discussion probe. The CoRe tool seeks to understand how
teachers conceptualize the content of a particular subject matter based on their experience of
teaching the topic—how, why, and what of the content is to be taught. Kind (2009) stated that
CoRe is the useful technique for eliciting PCK directly from a teacher, and the author points out
that “a completed CoRe provides a powerful means of recording the work of an experienced
teacher, available for sharing and exemplifying good practice” (p. 195). However, due to the
complexity of PCK required to complete CoRe, some teachers may not be able to respond as
fully as a researcher really needs (Kind, 2009). If a teacher has the opportunity to reflect and
share their ideas with other teachers and a researcher, the process will be less intimidating than
working alone, and teachers will gain new and more meaningful ways of learning about teaching
particular content (Kind, 2009; Loughran et al., 2006). Therefore, in phase I and phase II, a
discussions about learning and the teaching of genetics were planned as a group discourse,
allowing teachers share their experiences.
Examples of questions in the teacher interview protocol:
• How do you introduce the topic of genes to students? (Q.2)
• Reflecting on your experience in teaching genetics, what do your students typically know
about the gene when they come to class? (Q.10)
• What do you think genes look like? Please draw a representation of genes. (Q.12)
• Given representations related to genes, how do you use these pictures in your teaching and
what are the connections between these pictures? (Q.18)
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• Reflecting on the presented issue about students’ understanding of multiple models of the
gene, why do you think students have difficulty making connection across multiple models of
the gene? (Q. 20)
Discussions about designed learning materials. The purposes of the discussion session
on the designed tools were: a) to introduce teacher participants to the designed learning
materials; b) to assist teachers in interacting deeply with students’ understanding of multiple
models of genes; c) to revise and redesign the learning materials according to teachers’
comments; and d) to investigate teachers’ knowledge and pedagogical content knowledge.
Packages of designed instructional materials were distributed to teachers one week before they
attended the discussion. Teachers engaged in the discussion about multiple gene models,
students’ difficulties in learning molecular genetics, and instructional strategies to address the
issues of multiple gene models. Then, teachers engaged in the instructional design process
focusing on using representation as a teaching tool. An overview of the group discussion is
included in Group Discussion Program (see the Appendix). To document the design process,
video recording and audio recording were conducted with permission; field notes were taken
after the workshop. Examples of questions probing the discussion:
• What kinds of student misconceptions associated with the gene concept have you noticed
from the examples?
• Have you been challenged with the problem of students’ misunderstanding of multiple
models of genes in your classroom?
• How do you make connection across multiple models of the gene in your classroom?
• How do you think multiple linked representations of the gene should be used in teaching?
• Will you consider using these activities in your classroom? Why?
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In phase I and phase II, teachers participated in a four-hour group discussion to develop
and modify the tools. In phase II, four out of six teachers participated in the group discussion
(Kannisha, Montana, Teera, and Uma), while the others chose not to participate in the
discussion. The purpose of the discussion was also intended to create a social venue for teachers
to share their practices and concerns. According to social constructivism learning theory,
knowledge is socially constructed and that learning means that individuals are moving toward
full membership in the professional community (Novick & Hmelo, 1994). The discussion about
learning and teaching genetics was originally planned based on this idea; therefore, sharing and
exchanging ideas and experiences among teachers was encouraged throughout the design
process.
However, in phase III, the workshop format was changed to a 45-minute discussion
between an individual participant and the researcher due to conflicting schedules. Since the study
was conducted during the beginning of the semester and teachers faced increased workload, the
convenient date could not be set among participants. The discussion structure and questions were
maintained as occurred in phase II; the participants were asked to respond to a problematic
scenario regarding students’ learning about multiple models of genes and the designed
instructional tools. Although the advantage of social construction from group discussion was
missing, teachers in phase III shared more comments and suggestions about the designed
learning materials.
Classroom observations. In phase III, the participants were encouraged to implement
the designed tools in their classroom. The teachers could adapt the instructional tools based on
the needs of their classrooms and selected activities that they found helpful for their students.
Teachers could possibly have different levels of change in their instruction. Throughout the
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period of implementation, I supported teachers when they sought assistance with the learning
materials.
Classroom observations were conducted in the second semester (May to September).
Three out of five teacher participants in Banchang city were observed: Patcha, Salee, and
Wanida. Classroom observations were not conducted with the other participants because in those
schools genetic lesson would be taught in another semester. Moreover, to compare the
implementation, all teachers from phase II, Kannisha and Montana, were included to follow up
with their implementations in the classroom.
Classrooms were videotaped and audiotaped to identify instructional strategies that
teachers use; to explore how the nature of the gene is taught in the classroom; to discover
teaching practice about genetics in Thai high school classrooms; and to document the
implementation of the designed learning materials. The researcher paid attention particularly on
teachers’ use of multiple models in solving genetic problems during the observations. Based on
each teacher’s schedules, both the classical genetics class and the molecular genetics class were
observed. For each case, a total of five to seven class periods, lasted 10 to 12 hours were
observed. In some cases, the individual research contexts placed constraints and offered
affordances--sometimes unexpectedly--on the data that could be collected in a given
circumstance. For example, genetics classes of observed schools were taught at the same period
and classes were canceled due to school activities.
Follow-up Interviews. After the observation, 20-minute follow-up interviews were
conducted with five teacher participants who gave permission to classroom observations. The
teachers were asked to reflect on their teaching practices, students’ understanding of the gene,
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and the instructional tools. The interviews were video-recorded and audio-recorded with
permission.
Examples of questions in discussion about designed tools:
• If you plan to use the activities again, what would you like to change? (Q. 5)
• Do you think the activities help students have a better understanding of genetics? How? (Q.8)
• What difficulties did you experience in your teaching? (Q. 9)
• What changes would you make in these lessons next time? (Q. 12)
Student Interviews. In phase III, semi-structured individual interviews were conducted
with students from both classrooms with the intervention and the control classroom after the
instruction. The main aim was to measure high school students’ understanding of multiple gene
models, the use of multiple models, and their reasoning about genetic phenomena. Another goal
was to determine to what extent the outcomes of the developed tools were achieved by
correlating to instructions in the class. Three to five students were randomly selected from each
class; a total of 21 students was interviewed.
The student interview protocol was designed based on the interview protocol from my
master’s thesis. Students were asked to manipulate variations of representations of genes in their
explanation of genetic phenomena. Students were encouraged to think aloud as they explained
the genetic phenomena and solved problems by using both models of genes. The 25-minute
student interviews were conducted outside of the regular class periods. Video recording and
audio recording were conducted with permission.
Examples of questions in student interviews:
• Why is genetics important for you to learn?
• Explain how a given genetic trait is transferred to next generation.
• How can a gene cause a genetic disease?
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• What is the function of a gene?
• What happen with proteins after translation in protein synthesis process?
Data Analysis
Data analysis was divided into two parts. The first part examined teachers’ subject
content knowledge and pedagogical content knowledge regarding multiple models of the gene.
The second part studied the development of pedagogical tools for teaching multiple models of
the gene. Data taken from all aforementioned sources of evidence in the design-based research
were coded using NVivo version 10.0.303.0 (http://www.qsrinternational.com/).
One of the key ideas that informed the analysis was scientific modeling—the idea that we
understand science through the use of models and representations. By examining how models are
constructed and applied, it is possible for researchers to gain insight into how people
conceptualize science content. The analysis was first deductive, using a set of external codes
derived from the literature (i.e. the two models of the gene, the functions of the gene model, and
challenges in learning genetics). The participants’ responses were examined to determine the
degree to which they were able to demonstrate multiple models, integrate multiple models, and
apply multiple models to explain genetic phenomena. These external codes were then
supplemented with internal codes produced by an inductive approach as new themes emerged.
Analytic induction (Spradley, 1979) was utilized on these data to examine the successful use of
integrated multiple models in genetics education, the method of their integration, and factors
affecting teaching with multiple models in Thai classrooms. Through the process of constant
comparisons, the researcher established meaningful patterns, themes, and categories. The guiding
questions used for approaching the data are presented in the Table 11.
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Table 11
The Guiding Questions for Approaching the Data
Agent Focus Cognitive perspective Situated in classroom Educational constraints
Students
Content Knowledge
-What are common conceptions of the gene? -How they make connections between models?
How do students/ teachers apply the models to genetic domains?
- Why do students/teachers demonstrate a difficulty learning the gene concept?
Teachers
How does teacher content knowledge influence their teaching practice in the classroom?
Pedagogical Content Knowledge
-What do teacher big concepts -How teachers think about students’ prior knowledge/misconceptions? -What are instructional strategies teacher used in teaching genetics?
What are teaching strategies that teachers use to teach the gene concept in the classroom? (common/innovative)
What are relevant educational factors mediating learning and teaching genetics in the classroom? How?
Curriculum/Textbooks
Knowledge-centered approach
-What is taught? -Why it is taught? -How the knowledge should be organized to support the development?
How is the gene concept presented in the observed classroom?
Designed learning materials
Reflective approach
-What are effective strategies to facilitate students making sense of multiple models of genes and use gene models to explain genetic phenomena meaningfully? - What are examples of teaching practice regarding the gene concept?
-How do teachers implement the materials in the classroom? -How do the designed learning materials influence students’ learning of genetics?
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To illustrate, I presented the following examples of both external and internal coding
schemes. To examine construction of the gene model, participants’ responses were coded with
external codes based on the gene model found in high school curriculum. In order to examine
application of gene models, open-coding was utilized to unpack emerging themes. In the analytic
processes, coding schemes was developed and refined thoroughly to identify overarching themes
in discourse. Finally, synthesis analysis centered on the interrelation between these two sets of
categories was conducted to understand the knowledge structure regarding multiple models.
Examples of coding schemas
Coding for the default gene model:
a) The classical model: Evidence of classical model included a unit of inheritance,
an allele, or a part of chromosome.
b) The molecular model: Evidence of classical model included a sequence of
instruction, genetic information, a section of DNA coding for a protein.
Coding for the use of multiple models of the gene:
a) Separation: Responses were considered to have separation if the classical model
and molecular model were not presented together in one explanation or they
contained no explicit connection between the two models.
b) Partial connection: Evidence of partial connection included some connections
between two models, mostly structural connections. However, the models were
applied disjointedly to explain something.
c) Integration: The criteria of integration included the two models were presented
together in one explanation with explicit connections and were applied
concurrently to explain something.
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Multiple-case study analysis (Stake, 1995, 2005; Yin, 2009) was implemented to
compare consistencies and differences among cases, to gain a holistic view of teaching and
learning genetics, and to allow generalization of the findings. With cross case analysis approach,
scientific model conceptualizations and implementations of individual participants were
compared and contrasted across cases. Moreover, I compared students’ understanding from each
classroom to evaluate implementations of designed tools in various classroom settings; student
participants are embedded sub-cases which contribute to a more comprehensive understanding of
an issue or condition of cases (Yin, 2006). All sources of evidence were incorporated, and a
chain of evidence was developed in a triangulating fashion to establish a robust exploratory
analysis.
Due to rich sources of data and the nature of the study across educational contexts, the
analysis is restricted by the following constraints and limitations.
Linguistic constraint. Data collection from the phase II and the phase III was originally
conducted in Thai. All interviews and observations in these phases were transcribed and
analyzed in Thai. The selected compelling snippets of responses were translated into English.
When translating participants’ responses to another language, there may be a loss of the context
of word choices that renders a slightly different meaning. Therefore, due to this kind of linguistic
constraints, readers should be aware that translated passages may not perfectly represent the
subjects’ views. In addition, I tried to convey the similar meaning to participants’ responses as
possible in translation that may contain misunderstanding or vague ideas.
Data selection. With a large amount of collected data, I chose to focus my analysis
primarily on interviews, focus groups, and observations from the intervention implementation,
because this data was most closely associated with the phenomenon under investigation.
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Classroom observations without intervention implementation were only used to provide
background on the current teaching practices of participants. Moreover, the focus of this analysis
is to learn more about how participants use multiple models to understand genetics, not to
evaluate the scientific accuracy of their claims. Participant responses did contain many of the
misconceptions cited in the literature, but I have generally refrained from discussing these
scientific errors.
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CHAPTER 4
Exploring Teachers’ Knowledge about Multiple Models of the Gene
Introduction to the Chapter
This chapter presents the results of the study on Thai teachers’ content knowledge
regarding gene models and their pedagogical content knowledge in teaching genetics. To teach
all students according to today’s standards, teachers need to understand subject matter deeply
and flexibly so they can help students connect concepts together. Teachers need to see how ideas
connect across concepts and to everyday life. Teachers also are required to master pedagogical
content knowledge to make concepts accessible to learners. The analysis of the current state of
teacher knowledge and their teaching pedagogy reveals the need for professional development in
order to create a desirable learning environment for model connection. Moreover, the analysis
reveals essential learning principles for redesigning learning materials.
The data included teacher pre-interviews, surveys, and focus groups from Phase II and
Phase III. The total participants from the Rawai and Banchang sites were twelve teachers. This
section presents an analysis of teachers’ knowledge structure regarding multiple models of
genes. The focus is on how the teachers made sense of multiple models of the gene and applied
them in scientific explanations. The cross-case analysis of teachers’ conceptions of multiple
models of genes is presented to summarize the results. Last, a discussion of teachers’
pedagogical content knowledge regarding students’ conception of genes, students’ difficulties,
and teaching classical genetics and molecular genetics in Thai classroom is presented.
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Teachers’ Conceptions of the Gene
To explore teacher background knowledge, during the pre-interviews, the teacher
participants described and drew pictures to illustrate their ideas of genes (see questions below).
The results from verbal/written answers and drawings revealed that the teachers had multiple
ways of conceptualizing the gene, such as a unit of inheritance, a DNA section, and a nucleotide
sequence. The teachers as experts in high school biology curricula demonstrated a concrete
content knowledge of structure and function of genes and genetic phenomena; there was no
instance of major scientific misconceptions, unlike the student results.
Interview questions on teacher ideas of the gene
• What is a gene? What is the function of the gene? • How can a gene cause a genetic disease? • What do you think genes look like? Draw a picture of genes.
It is important to note that, during the interviews, all participants demonstrated
knowledge of both classical and molecular models at some points and they were able to use both
models to explain genetic phenomena comprehensively. The integral analysis of their use of
multiple models will be discussed in detail in the next section. The analysis in this section,
however, will focus only on specific models that the teachers used to describe the meaning of the
gene and its function in listed questions. The analytic objective is to disclose teachers’ dominant
understanding of the gene—the salient model that they are likely to think of first. This detailed
perusal is used for case comparison (both to cases in this study and to those identified by other
studies) and for the cross-case analysis on whether teachers’ default model influences the types
of connections between the models they constructed.
Description of the gene. When asked to describe what a gene is, seven out of twelve
teachers defined a gene as a sequence or a section of DNA coding for a protein (see Table 12).
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These statements were coded as the molecular model because they were associated with
sequences of instructions and gene expression. Five out of twelve teachers defined a gene as a
unit of inheritance for genetic transmission, which was coded as the classical model.
The functions of genes associated with the classical model and those associated with the
molecular model were significantly different. According to the textbook analysis in the literature
review, the notion of gene function conceptualized by these teachers is identical to the way gene
functions are presented distinctly in two units of the Thai curriculum: the classical model for
genetic transmission and the molecular model for gene expression.
Most teachers who used the classical model described a gene as a passive particle, rather
than an active particle (except TB3-Wanida); its function as limited to being inherited to next
generation. In contrast, all teachers from the molecular group described gene function as actively
producing proteins for cellular processes in everyday life; this suggests that the teachers with the
molecular model automatically think of the sequence as entailing the next step in transcription
and translation. None of the teachers from the classical model group mentioned proteins as
intermediates from genes to phenotypes, because the classical model has no power to explain a
cause of gene expression. Indeed, a function of the molecular model also can be passive such as
transferring genetic information to the next generation. The following quotes illustrate different
functions of genes associated by teachers:
• Passive classical model: “The function is to control a genetic trait passed from
generation to generation” (TR3-Teera).
• Active molecular model: “The function of a gene is to control protein synthesis in the
body so that those proteins have functions for livings [sic]” (TR6-Atita).
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Table 12
Teachers’ Descriptions of the Gene and the Function of the Gene
Teachers’ Descriptions of the Gene Classical gene model
TR2-Montana A gene is a unit of genetic trait [sic.]. A gene has a function in controlling transmission of a genetic trait.
ยน คอหนวยของลกษณะทางพนธกรรม ยนมหนาท
ควบคมการถายทอดลกษณะทางพนธกรรม
TR3-Teera A gene is a unit of heredity. The function is to control a genetic trait passed from generation to generation.
ยน คอหนวยทางพนธกรรม ทาหนาทควบคมลกษณะ
ทางพนธกรรมทถายทอดจากรนหนงสอกรนหนง
TR4-Malee A gene is a genetic trait passed from generation to generation. The function of it is to control a genetic trait to show in each generation correctly.
ยน คอลกษณะทางพนธกรรมเปนการถายทอดจากรนส
รนไปเรอยๆ หนาทของมนกคอควบคมลกษณะทาง
พนธกรรมใหปรากฏออกมาแตละรนๆ อยางถกตอง TB3-Wanida A gene is a unit that controls a genetic trait.
A gene is a section of DNA. ยน คอ หนวยททาหนาทควบคมลกษณะทางพนธกรรม ยนเปนสวนหนงของดเอนเอ
TB4-Sukan A gene is a unit of heredity that brings a trait that is a particular trait. A genetic trait that can be transferred. A gene is a passenger. For example, a guy has an amputated finger. Amputated finger cannot be passed; therefore this trait is not a genetic trait.
ยนกคอ หนวยพนธกรรมทจะนาลกษณะตางๆ เปน
ลกษณะเฉพาะ ลกษณะพนธกรรมทจะถายทอดไปได ยนจะเปนตวพาไป ถาผชายคนนนนวดวนอยางน ลกษณะนวดวนไมพาไปกแสดงวาลกษณะนนไมใช
ลกษณะพนธกรรม Molecular gene model
TR1-Kanisha A chromosome is a long DNA string. Genes are parts of DNA that can code for proteins that can be used for being compositions of the body. The question is to draw a picture of genes. I therefore coded this part and zoomed out to show a structure of DNA molecule. Assuming that this part of DNA coding for something.
โคโมโซมมนกคอสาย DNA ยาวๆ แตวายน คอสวน
หนงของ DNA เปนสวนทโคดใหโปรตนทสามารถ
นาไปเปนสวนประกอบของรางกายได อยากใหจะให
วาดรป ยนกเลยโคดสวนนออกมาและขยายออกมาให
เหนโครงสรางของโมเลกลของ DNA และเรากสมมต
วาสวนนเปน DNA ทสามารถโคดใหอะไรได
TR5-Uma A gene is an element on a chromosome. The function is to produce a protein that brings about a structure of the body.
ยนคอ องคประกอบทอยบนโครโมโซมทาหนาทสราง
โปรตนซงโปรตนมผลตอลกษณะโครงสรางของรางกาย
TR6-Atita A gene is a part of DNA that a base sequence is transcribed to the one synthesizing a protein. It is a unit that has function in controlling a genetic trait in organisms. The function of a gene is to control protein synthesis in the body so that those proteins have functions for livings.
ยนคอเปนสวนหนงของ DNA สวนทลาดบของเบส
ถอดรหสมาแลวเปนตวทใหสรางโปรตนคอหนวยททา
หนาทควบคมลกษณะทางพนธกรรมของสงมชวต หนาทของยน ควบคมการสรางโปรตนในรางกายเพอให
โปรตนเหลานนทาหนาทตางๆ เกยวกบการดารงชวต
TB1-Patcha A unit controlling the expression of traits in organisms. It is a base sequence that is an agent for genetic information for building a protein.
หนวยควบคมการแสดงออกของลกษณะตางๆ ของ
สงมชวต มนคอลาดบเบสทเปนตวการใหเกดเปนรหส
พนธกรรมเพอสรางโปรตน
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Tabel 4.1 (Continued)
Molecular gene model TB2-Salee A gene is a base sequence on DNA that
controls protein synthesis or makes one strand of polypeptide. The function of the gene is to control genetic traits of organisms.
ยนคอลาดบของเบสบน DNA ทควบคมการ
สงเคราะหโปรตนหรอ polypeptide ได 1สาย หนาทของยน คอ ควบคมลกษณะทางพนธกรรมของ
สงมชวต TB5-Nampen A gene is a unit of heredity. A
unit controls the expression of genetic trait. If a gene or a sequence of a gene that control a trait is abnormal, protein synthesis for various elements, the expression of traits will be abnormal as well.
ยนกคอหนวยพนธกรรม หนวยทควบคมการแสดงออก
ของลกษณะทางพนธกรรม ถาหากวายน หรอวาลาดบ
ของยนทควบคมลกษณะมนผดปกตไปการสงเคราะห
โปรตนเพอทจะเอามาเปนองคประกอบตางๆ การ
แสดงออกลกษณะตางๆมนกจะผดปกตไปดวย TB6-Pakorn A gene is a sequence of nucleotides. The
shape is uncertain. It is a part of DNA. A gene is a unit controlling genetic trait. A function is to control genetic traits by regulating the synthesis of matters.
ยนคอลาดบนวคลโอไทด รปรางไมแนนอน แตเปนสวน
หนงของดเอนเอ ยนคอหนวยควบคมลกษณะทาง
พนธกรรม หนาทคอควบคมลกษณะทางพนธกรรมโดย
ผานทางการควบคมการสงเคราะหสารตางๆ Note. Red text with dotted underline indicates the classical gene model. Blue text with underline indicates the molecular gene model.
Drawings of the gene. Drawing genes allowed the teachers to demonstrate various forms
of representations, such as symbolic DNA sequence, and to talk about relations between different
models. Many teachers initially expressed that they were not sure how to draw a picture of a
gene due to its abstraction; Sukan finally decided not to draw any picture of genes.
The analysis of drawings revealed the similar result that most teachers conceptualized
genes from the molecular view. Ten out of eleven teachers illustrated the molecular gene model
with a DNA structure containing a sequence of instruction (see Table 13). Only one teacher,
TR2-Montana, retained the classical model with a drawing of homologous chromosomes and
locations of alleles. Although some molecular pictures did not explicitly portray nucleotide
sequences, the teachers mentioned sequences in their explanations about their drawings. The
molecular representations included a double helix DNA, a ladder DNA, and a double strand of
nucleotide sequence; these visual representations depict different characteristics of DNA.
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Table 13
Teachers’ Drawings of the Gene
Classical model representation Molecular model representation Multiple representations
Note. Teachers’ drawings captured from the questionnaire. Formatting on teacher names represents coded models from the analysis on verbal description of genes. Red text with dotted underline indicates the classical model group. Blue text with underline indicates the molecular model group.
TR6-Atita
TB3-Wanida
TB5-Nampen
TB6-Pakorn
TR5-Uma
TR3-Teera
TR4-Malee TB1-Patcha TB2-Salee TR1-Kanisha TR2-Montana
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For TR4-Malee and TB3-Wanida, there is a disagreement between their verbal description and
their visual representation; they first described the gene according to the classical model and then
drew representations of molecular model instead. This suggests that the teachers have a set of
conceptions of the gene that they could choose to represent.
Interestingly, the drawings by TR1-Kanisha, TR3-Teera, and TR6-Uma to some extent
depicted multiple representations of genes that contained the elements of both classical and
molecular models. The teachers drew a chromosome (classical model) and a polynucleotide
chain (molecular model). These multiple representations are evidences of connections between
the classical and molecular models. These cases will be further discussed in the next section
about connecting multiple models.
To sum up, the findings from both verbal and visual representations confirm that the
teachers’ salient model of the gene was the molecular model. The results differ from the results
from previous research on students’ understanding of genes in which most students demonstrated
the classical model and had difficulty applying the molecular model even after the instruction
(Auckaraaree, 2009; Duncan & Reiser, 2007; C. Tsui & Treagust, 2007; Venville & Treagust,
1998). Students’ drawings and statements did not clearly depict nucleotide sequences of the
molecular model (see Figure 7). The finding suggests that teachers as experts, compared to
students, promptly depicted the gene as a sequence of instruction in their explanation and they
retained the molecular model as their main idea. This confirmed the hypothesis that teachers
acquire extensive knowledge about the molecular model and the ability to retrieve the model in
order to explain genetic phenomena with ease, unlike students. This is also an important pre-
condition for the focus groups that teachers attended to design the learning materials.
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Figure 7. Examples of descriptions and drawings of the gene by Thai high school students from
the previous study (Auckaraaree, 2010)
Teachers’ Use of Multiple Models of the Gene
Based on the literature review, the current high school curriculum presents multiple
models of genes in separate contexts without explicit connection. The questions raised by this
research are a) how teachers apply these multiple models of genes in their explanation and b)
how teachers make connections between models. The purpose of studying teachers’ knowledge
of multiple models is to understand current problems in teaching multiple models, identify
possible teaching strategies, and improve professional development. The analysis centered on
connections teachers constructed between the classical model and the molecular model during
the interview before the workshop. Teachers also responded to a set of questions that required
them to connect multiple models. For example, the teachers described how the picture A of the
Genes are on chromosomes. The sections of chromosomes that control genetic traits. DNA is a
stand coiled to be a chromosome.
Genes are the sections of DNA. Chromosome is composed of DNA.
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classical model relates to the picture B of the molecular model (see Figure 8). The ways teachers
used multiple models of genes are categorized into: a) separation, b) partial connection, and c)
integration.
Figure 8. Representations of genes in the interview task for eliciting connection between the
models. Picture A presents the classical model and picture B presents the molecular model.
a) Separation. The findings revealed that, before asking the interview questions designed
for eliciting their connections, most teachers employed the classical model and the molecular
model separately. The classical model was used in relation to the genetic inheritance domain; on
the other hand, the molecular model was used in relation to the gene expression domain. The
teachers did not demonstrate any instances of direct connections across two models, similar to
the way that the gene concept is presented discretely in the curriculum within each particular
domain.
When the question (such as one about teaching and learning genetics in general) did not
lead to a particular model, teachers seemed to have a preference for one model —the model that
they used as their default explanation. This matched the coded default model they used to
described the gene, discussed in the previous section. For example, TR4-Malee, who was
categorized in the classical group in the previous section, mainly referred to the classical model
Picture A Picture B
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when she talked about genetic phenomena, teaching genetics, and student learning. Note that
further analysis of the models most frequently used in the explanations throughout the interviews
is still needed.
Whereas most teachers later demonstrated some evidence of connections when explicitly
prompted to do so, TR2-Montana and TB4-Sukan struggled to make explicit connections
between models. The teachers saw each domain being explained by one particular model only.
This markedly indicates that the classical and molecular models were not integrated in these
cases.
The following excerpt from the interview with Sukan shows that discourses around each
model were associated with different scientific terms and situated within particular genetic
domains. While the classical model excerpt contained chromosomes, alleles, genotypes, and
phenotypes, the molecular model excerpt contained DNA strands, sequences, codes, bases,
proteins, and information.
With the classical model Interviewer: How do you explain students when you have to tell them what a gene is or what is a function of it? Sukan: When I teach students, I will tell them that the real gene that we see as a shape of the Chinese crullerP6F
7P
is only a replication. It composes of two chromosomes and connects with centromere (sic.). When we see one chromatin like one strand of Chinese bread, it actually is fiber. Tell students it is fiber like this and genes locate on here. A couple of the gene is called that they are alleles. The couple that Mendel represented with TT or Tt or tt. These are called genotypes that are carried. Themselves are genotypes, are genes. They then carry traits inside genes that called genotypes. This leads to phenotype that expressed outside.
Interviewer: อาจารยตองอธบายใหนกเรยนฟงวา gene คออะไร หรอวา หนาทคอ
อะไร อาจารยจะอธบายวายงไงคะ
Sukan: ออ เวลาทจะสอนเดกเนย บอกเดกวา gene หนาตาจรงๆ ทเราเหนเปน
รปราง ปาทองโก เนยมนเปนภาพจาลองเฉยๆ วามนประกอบดวย 2 Chromosome แลวยดตดกนดวย เซนโตเมย เรามองดเนยเหมอน โครโมตนหนงเปนเหมอนแทง ปาทองโกแตของจรง ไมใชมนจะเปน
เสนใยแบบนคะ บอกเดกวามนเปนเสนใยแลว gene จะอยบนนนะ แลว gene รปคน เคาจะเรยกมนวา อลลน กนแลวคเนยท mendel แทนดวย TT หรอ T tหรอ tt เพราะฉะนน เราจะเรยกมนวา genotype ทจะนาพาซงมนตวมนเองเปน genotype เปน gene กอนแลวคอยจะนาพาลกษณะทอยภายใน gene เรยกวาgenotype จะสงผลใหปรากฏ phenotype ทปรากฏลกษณะภายนอก
7 This metaphor is commonly used in Thai classrooms. Due to the similar shape, Thai teachers compare chromosomes to Chinese crullers )ปาทองโก( , also known as Chinese doughnuts (see a sample picture at http://www.foodtravel.tv/recfoodShow_detail.aspx?viewId=1321)
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With the molecular model Interviewer: What are strategies that you used or would like to suggest in order to help the student make connections from DNA to protein? (after a discussion on a case of a student who could not link DNA to a protein) Sukan: I will use pictures of cell with big nucleus and I will draw a picture of DNA. In case of regular cell division that DNA strands separate into two strands, right? I will draw both strands of DNA with bases. There is ‘A’ pairing with ‘T’. The new strand is with bases as codons, in a set. I will draw picture for students. If DNA template and new replicated strand, I will divide into two equally. The first one is the main and the second DNA strand is the new one we build, right? …If we will build a protein, this is not it. The first strand is DNA and the second one is mRNA. There is no ‘T’. It will be ‘U’. …When we have a scare, there will be an order to build, right? Building a protein to fix our fingers. Therefore, it need to transcript codes that a finger is composed of what proteins. A code is transcript in mRNA. It is small so it passes pores. Since it is a messenger sending information. … When the building is finished, it will travel to fix a finger.
Interviewer: อาจารยมกลยทธยงไงหรอวามวธการสอนยงไงบางทใหเดกเขาใจ ท
อาจารยเคยใชอยหรอวา อยากจะแนะนา Sukan: เรากจะใชวาดภาพเปนรป cell รป cell ทมนวเคลยสอนโตๆ แลวกจะ
วาด DNA กอนถาในกรณของการแบง cell ธรรมดาใชมยคะ ทวา
มนตองแยกเสน DNA มาเปนสองเสนใชมยคะ เรากจะวาด DNA ทงสองเสนโดยมเบสใชมยคะ โดยม A จบคกบ T ปกต แลวกสวนน
มนสรางใหมกใหมนเปนเบสทเปน โคดอน เปนชดๆ ไปอยางเนย เคาก
จะสรางแบบจะวาดภาพใหเดกรวา ถาเสน DNA มนเปนแมแบบกอน แลวไอตวใหมทสรางขนมาร ทจะแบงเปนสองสวน เทาๆ กน เนย เพราะวา เสน DNA เสนแรกจะเปนตวหลก แลวเสน DNA ทสอง
จะเปนตวทเราสรางใหม ใชมยคะ …แตถาเราจะสรางโปรตน ไมใช
แบบนแลว เราจะเสนแรกเปน DNA เสนทสอง จะเปน mRNA ซง
มนจะไมม T มนจะมแค U … ขณะนเรามบาดแผลแลวเรยบรอย มน
กม order สรางใชมยคะ สรางโปรตนมาซอมทนวเราเพราะฉะนน มน
กตองพมพรหสขนมาวา โปรตนทนวมนจะประกอบดวยอะไรบาง โดย
พมพรหสกบ mRNA แลวเลกมนกจะลอดรมา เพราะมนเปน messenger จงเปนผสอขาวสงมา … แลวพอมนสรางเรยบรอยแลว
มนจะเดนทางนะคะ ไปซอมนวนะคะ
When Montana and Sukan responded to the prompts to make explicit connections, they
failed to establish connections even when they acquired multiple models of the gene. They stated
that both representations of genes described the same biological matter, without making further
connections. Montana began with a vague idea equating a gene with a trait. She struggled to
elaborate how an idea of the gene as a sequence with a function in protein synthesis (the
molecular model) was related to her drawing of alleles on chromosomes (the classical model).
She was also confused about how to identify the molecular gene—in other words, how to
determine a length of DNA sequence as one gene. She believed that, compared to the picture of
alleles, the sequence in the picture B should have been longer.
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Interviewer: Can you explain your drawing? Montana: I’m not sure if this is correct. I think genes are in chromosomes, on these points. Interviewer: So, these highlight sections are genes Montana: In one chromosome, it may compose of many genes. Gene is a unit of genetic trait. This gene functions in controlling a transfer of genetic traits. But, I’m not sure because genes also can determine protein strands that represent characteristics of genetics. Assuming DNA strand also has an impact on transferring genetic traits. I’m not sure if this is correct. … Interviewer: What do these two pictures mean? Are they related? Can you please explain? Montana: We need to know a sequence to determine a gene of livings. Therefore, if the sequence of this organism is one gene (picture B). It will be equal to this one gene (picture A). Therefore, each organism will have different sequences. Interviewer: So, you think this piece is gene (picture B) and this one they represent with highlighted parts (picture A). Montana: Yes, but picture B should be longer. DNA is long coiled strand. If we assume DNA is short, students will know only that. In fact, it should be long and coiled. But, I did not teach in dept. My knowledge is not deep enough to know how long a base sequence should be. Just like in the test. I had a problem about cutting in mutation (sic). I don’t know how they cut by using enzymes. Interviewer: Do you mean when you solve problem about biological technology, cloning, and those staffs? Montana: The exam gave base sequences and enzymes, and it asks to find it happens at what sequence. I had a problem, because I don’t know much on this topic. Interviewer: What does the picture A mean? Montana: From my understanding, it is a gene. For example, this one is having dimple and this one is not having dimple. If we look at DNA structure, it is about dimple.
Interviewer: อาจารยชวยอธบายภาพทอาจารยวาด
Montana: ไมแนใจถกหรอเปลา อนนกคอเขาใจวา gene อยในโครโมโซมคอจดน Interviewer: คอชนสวนทอาจารยขดๆ ตรงนคอสวนของ gene Montana: ในหนงโครโมโซมอาจจะประกอบดวย gene หลายๆ gene และอนน
จะเขยนวา gene กคอหนวยของลกษณะทางพนธกรรม และอนน gene กทาหนาทควบคมการถายทอดลกษณะทางพนธกรรม แตไมมนใจ คอแบบวาหมายถง gene กสามารถกาหนดสายของโปรตนทแทน
ลกษณะของพนธกรรม ถาสมมตวาสายของ DNA กมผลตอการ
ถายทอดลกษณะทางพนธกรรมออกมา ลองดนะคะวาถกหรอเปลา… Interviewer: สองภาพนหมายถงอะไร และสองภาพนมความสมพนธกนหรอไมและ
สมพนธกนอยางไร อยากจะใหอาจารยอธบายเพมเตม Montana: เราตองรลาดบเบสในการกาหนด gene ของแตละสงมชวต เพราะฉะนน
ถาสมมตวาลาดบเบสของสงมชวตอนนเทากบ 1 gene มนกจะมาเทากน
กบ1gene เพราะฉะนนคอสงมชวตแตละชนดลาดบเบสกไมเหมอนกน Interviewer: อาจารยมองวาชนสวนตรงนทเปน gene และตรงนคอสวนทเขาแทน
ตรงสวนทเปนไฮไลทในจดๆ น Montana: ใช แตมนนาจะยาวกวานนะ เพราะวามนสนขนาดน DNA มนมวน
เยอะมากนะ เพราะฉะนนจรงๆ การศกษามนเหมอนเรยงปญหา ถาสมมต
วาเราทา DNA ใหมนสนเดกกเขาใจสนๆ มนกเขาใจเทาน แตจรงๆ มน
ไมใชมนตองสายยาวเพราะวามนตองมวนเยอะ แตจรงๆ อนนไมไดลงลก ความรตวเองไมไดลงลกมากไปถงวาลาดบเบสมนเทาไหรๆ เหมอนกบขอสอบบางครงทตดมวเทชนทาแลวกจะมปญหาทกท ไมรวา
เขาตดอยางไร ใหพใชเอนไซนแตละตวตด Interviewer: หมายถงวาเวลาททาเทคโนโลยชวภาพพวกโคลนนงอะไรอยางนใชไหม Montana: ขอสอบทมนบอก ขอสอบเขาจะบอกบลาดบเบสมาใหและกใชเอนไซม
ตวนตดสนเทาน และโจทยกใหหาวาเกดลาดบทเทาไหร คอมปญหากบ
ตวเองเหมอนกนแหละในการทจะใช ปนเพราะวาเราไมคอยลกเรองน Interviewer: อยางภาพนอาจารยบอกวาแสดงถงอะไรนะคะ Montana: อนนทเขาใจกคอ อนนเปน gene สมมตวา gene เกยวกบลกยม อนนก
ไมมลกยม สมมตวาไปดเกยวกบโครงสราง DNA ไอแคนกคอลกยม
Note. Red text with dotted underline indicates the classical gene model. Blue text with underline indicates the molecular gene model. Bold text indicates coded connection between models.
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b) Partial connection. Although teachers tended to separate multiple models before
providing explicit prompts to make connections, eight out of twelve teachers showed partial
connection between multiple models after the prompts. This group of teachers made the
connection in terms of biological structure but not function. To connect multiple representations,
they explained that a DNA sequence is located in chromosomes in cells, as shown in the excerpt
below. Their explanation of gene matter involved the action of expanding or narrowing the focus
on different panels. This suggests that they used multiple gene models to represent the gene at
different biological levels.
Interviewer: Do you think these pictures are related? How? Kanisha: These two pictures are related. This one is a chromosome. If we expand a chromosome, there will be DNA look like this. ‘A’ is a gene. It is a part of DNA. It is only that this part is coiled very tie turning into chromosome. Interviewer: Do you think students can make connections like you did? Explaining that sequence in chromosome is the section. Kanisha: If we tell students at first that genes are parts of DNA and we teach them that one stand of chromosome is one DNA that is coiled very tight, students will be able to make connection. However, if we do not tell them at first, they will not understand.
Interviewer: อาจารยคดวาสองภาพนเชอมโยงกนหรอไมคะ อยางไร
Kanisha: สองภาพนกสมพนธกนนะคะ เพยงแตวาภาพนมนอยในลกษณะของ
โครโมโซม ถาเราดโครโมโซมทยดออกกกลายเปนเสน DNA ทหนาตาเปนแบบน สวน R ทบอกวาเปนgene เปน DNA กคอสวน
นนนเอง เพยงแตวาตรงนมนขดมนมากจนกระทงกลายเปน
chromosome Interviewer: แลวอาจารยคดวานกเรยนเขาสามารถสรางความเชอมโยงอยางทอาจารย
อธบายไดไหมคะวามนคอลาดบทอยในโครโมโซมมนกคอชนสวนตรง Kanisha: ถาเราบอกเดกไปตงแตตนวา gene มนคอสวนของ DNA แลวเราก
ตองทาความเขาใจกบเดกดวยวา โครโมโซม 1 แทง มนคอ DNA 1 เสนทแคขดแนนๆ เฉยๆ นะอะไรอยางนเดกกนาจะเชอมโยงได แตถา
เราไมพดตงแตแรก เดกเขาดใหตายอยางไรกไมรเรอง Interviewer: What do you think would be students’ answers on what a gene is? Patcha: If students explain, they will say ‘a’ is a gene. It is a gene expressed in germ cells. This is recessive. Then, in this picture B, it talks about Ugene located on DNAU. This section is a gene. This gene controls the same trait with the previous one. The picture A and the picture B are related. Actually, it likes we expand and get in dept. Zoom in more. Showing how it looks. From here it will be nucleotides. We can get more in depth continuously, because we can expand from
Interviewer: อาจารยคดวานกเรยนจะตอบวายนคออะไร
Patcha: ถาเดกเขาอธบายกจะบอกวา R กคอ gene เปน gene ทจะแสดงออก
อยในเซลลสบพนธ เปนลกษณะเดนลกษณะดอย และพอมาถงรปบ กจะ
พดถงวาอนนคอ gene ทมนอยบน DNA วาชวงตรงนเปน gene gene หนงทควบคมลกษณะอนเดม ทงรป A และ รป B มความสมพนธกนจรงๆ มนกคอตวทเหมอนกบเราขยายจดใหลกเขาไป
อก ซมเขาไปอกวาตรงนเปนอยางนหนาตาเปนอยางนและตรงนไปจะม
ลกษณะเปนนวคลโอทายนของแตละอน วาแตละอนสามารถทจะลกไป
ไดเรอยๆ เพราะจากโครโมโซมกมาขยายเปนสายของ DNA ทมนมา
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chromosomes to DNA strands. This is relates to this picture B. If we zoom in more, inside ‘T’, you will found sugar, phosphate. Here is also connecting. It depends on how we are going to look at what levels.
ผกพนกนใชไหมกเปนอนน พอขยายอนนไปอก ใน T กจะรวาตองม
นาตาล ตองมฟอสเฟสกมความสมพนธกน เพยงแตวาเราจะมองแค
ตรงไหน
Note. Red text with dotted underline indicates the classical gene model. Blue text with underline indicates the molecular gene model. Bold text indicates coded connection between models.
This type of partial connection between the classical and molecular models is commonly
found in current high school genetics curricula. At the beginning of a typical molecular genetics
chapter, students learn about structure and location of DNA. This structural connection from
chromosomes to DNA molecules helps students associate a location of the molecular gene to a
cellular level (see Figure 9).
Figure 9. Partial connection between classical and molecular models. Pictures are adapted from
Thai high school textbook Biology by the IPST, p. 58 and p 60.
During the workshops on designing the learning materials, the participants were asked to
suggest teaching strategies they believe will foster students’ coherent understanding on the gene.
The teacher participants from the U.S and Thailand referred to this graphic connection strategy
as the way to incorporate various models into a big idea. However, my literature review in
Chapter 2 has shown that bridging strategies of this type do not help students to construct a
complete picture of the gene concept. The limitation of this strategy is that it does not reach to
Allele (A,a)
Genotype (AA, Aa, aa)
DNA sequence
(5’ATCTGGTCTTA3’)
Symbolic mode Visual mode
Cellular level Molecular level
Symbolic mode
X X
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the level of function—completely lacking, for example, an explanation of how alleles in
chromosomes are associated with sequences of instruction. The teachers did not draw
connections from visual representations to symbolic representations of alleles or DNA
sequences.
Due to partial connection, the teachers viewed multiple models as having different levels
of explanatory power for representing phenomena scientifically. Atita viewed the symbolic
classical gene as a hypothetical unit and only the molecular model as real matter that can
function. She thought that the molecular model accounts for real genetic phenomena. In fact, a
sequence of genes is also a model representing genes at the molecular level.
Atita: These two pictures should be related, because they are the same thing. This part (picture B) could be this part or this one (picture A-pointing at left and right parts of chromosomes). Interviewer: Do you mean it could be only one of the highlighted parts? Atita: Is it correct? Assuming this location is a gene controlling all characteristic of height. We assume a gene to be this one (picture A). It is an imagination. Another one (picture B) is a real thing. … Interviewer: Can you please draw a picture illustrating the relationship? You said this strand is inside this. The picture is compressed. Atita: Yes, we need to understand it is pressed. When we extend it, it will look like picture B. Interviewer: How about the letter ‘A’? Atita: This one is only the assumption. Actually, the sequence of gene is a gene that functions in controlling height. However, when we explain that in our body height is controlled by a gene. We are just assuming that our gene locates here, creating symbols. Therefore a location of the short gene should be this one (pointing at ‘a’).
Atita: สองภาพนกเกยวนะ ถาดเพราะวาถาจรงๆ ตวนกบตวนมนคอตวเดยวกน แตวาตวนคอนคอ gene ชดนกคอสวนนหรอสวนน Interviewer: ตวใดตวหนงกคอสวนทไฮไลทมาตรงนใชไหมคะ Atita: ใช ถกไหม สมมตวาตวตาแหนงนมนเปน gene ทคมความสงทงหมด
น เรากสมมตใหมนเปนตวน อนนคอตวสมมต อกอนเปนตวจรงเขาใจ
วาอยางนน… Interviewer: อาจารยลองวาดภาพประกอบกไดคะวามนสมพนธกนอยางไร ทอาจารย
บอกวาตรงนกคอเสนนใชไหมคะ ภาพนมนยอมาจากขางในน Atita: ใช มนตองเขาใจมนกคอตวนทมนกดอย ฉะนนพอเรายดออกมามนกคอ
ตวน Interviewer: แลวตวอกษรเอ Atita: ทนมนเปนตวสมมตแตวาตรง gene สาดบเบสตวนมนเปนตว gene ททาหนาทคมความสง แตเวลาทเรามาอธบายวาตวเราทความสงมนถก
ควบคมโดย gene มนเปนตวสมมตวาไอ gene คนเรามนอยตรงนคอ
ตวน กาหนดสญลกษณ เพราะฉะนนถาตาแหนงนม gene เตยอยมน
ตองเปนทตวน
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To illustrate the limitation of having a partial connection in detail, I present two cases:
TR2-Teera and TR5-Uma. These selected cases illustrate a potential difficulty in merging
multiple models of the gene. These teachers acknowledged both models by drawing multiple
representations of classical and molecular models; however, the connections between classical
and the molecular models were ambiguous. Teera and Uma struggled to explicate complete
connections.
Teera. At first, Teera struggled with how to draw a picture of a gene and decided to draw
multiple representations of a section of chromosome indicating allele ‘A’ and a double DNA
helix (see Figure 10). He then added the DNA strand after answering other interview questions
about student learning. He said ambiguously that a gene is also related to DNA. To answer how
these drawings are related, he said that DNA is coiled into a chromosome, and the highlighted
section corresponds to a gene at locus ‘A’. His drawing potentially represented multiple models
of genes; however, any functional component of the molecular model was missing from his
explanation about his drawing as shown in the following excerpt.
Figure 10. Teera’s multiple representations of gene.
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Interviewer; What is a gene? Teera: Gene is a thing that controls a genetic trait, and it has. Hmm. Interviewer: You can think first. It is like how you explain students what a gene is. Can you please explain your picture? What does it mean? Teera: I’ve just drew a picture. This is a chromosome. This part is just a location of chromosome. Want to tell this is a gene. Interviewer: So, a gene is this part in a chromosome. Teera: Yes … Interviewer: How do you make connection between these? Teera: DNA is a composition of chromosome. It is coiled. During cell division, a shape of chromosome will be clearer. A strand of DNA is coiled around histone proteins. It should be related to a gene. I am not sure how to draw a picture. However, it needs DNA strand and a shape of chromosome. Interviewer: Is DNA a part of this (a picture of chromosome)? Teera: A part of chromatid. Chromatid is a composition chromosome. Interviewer: So, DNA is inside this piece? Teera: Yes Interviewer: What does ‘A’ indicate? Teera: ‘A’ is a gene. Depicting as gene ‘A’. It is located on this part of chromosome. Not sure if it can be showed like this. This is a location of gene on chromosome. This (a picture of DNA) showed that a strand of chromosome is a coiled strand of DNA. Interviewer: How is ‘A’ part related? Teera: As I saw, this is very small and it is coiled and the strand is packed.
Interviewer ยนคออะไรคะ
Teera: gene กคอตวทควบคมลกษณะทางพนธกรรม และกม เออ Interviewer: ลองคดดกไดคะ เหมอนกบเวลาอาจารยตองอธบายใหนกเรยนวา
พนธกรรมคออะไร gene คออะไร อธบายใหจากรปใหฟงหนอยได
ไหมคะวาตวไหนคออะไร Teera: อนนผมกวาดรปเฉยๆ สวนนคอแทงโครโมโซม สวนนคอตาแหนงของ
โครโมโซมเฉยๆ อยากใหรวาตรงนกคอ ยน Interviewer: gene กคอชนสวนสวนหนงทอยในโครโมโซม Teera: ใชครบ … Interviewer: อาจารยเชอมโยงอยางไรคะ
Teera: DNA คอสวนประกอบของโครโมโซม ทขดพนกน ทชวงการแบง
เซลลรปรางของโครโมโซมกชดเจนขน กจะเหนสายของ DNAซงพน
รอบโปรตนhistoneอย ซงมนกนาจะมยนทเกยวของกน คดไมออกวา
จะวาดภาพมาอยางไร แตวาจะตองมสาย DNA และรปรางโครโมโซม Interviewer: DNA กคอสวนหนง Teera: กคอสวนของโครมาตน โครมาทด ทเปนสวนประกอบของโครโมโซม Interviewer: แลว DNA กคออยในแทงน Teera: ใช Interviewer: แลวสวนของ A Teera: A กคอยน แทนวาเปนยนเอ ซงมนอยบนสวนนตาแหนงนของ
โครโมโซม ไมรจะถายทอดออกมาอยางนไดหรอเปลา คอมนกคอ
ตาแหนงของยนบนโครโมโซม อธบายออกมาวาแทงของโครโมโซมก
คอสาย DNA ทพนกนอย Interviewer: แลวสวนAนเกยวของกนอยางไรคะ
Teera: เทาทเหนอนนจะมขนาดเลกมากและมนกพนกนเขามาและกเปนสายทม
การอดแนน
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When Teera was asked how the pictures of genes were related (see Figure 8: the picture
A of the classical model and the picture B of the molecular model), he said that “These two
pictures are the same but they have different nature”. He began to mention a base sequence and
polynucleotides. However, he was confused about how to connect the two pictures beyond the
fact that DNA is part of a chromosome at the structural level. Based on his drawing, Teera
successfully connected the symbolic classical model to chromosomes, but he failed to elaborate
connections from the DNA molecule to the symbolic molecular model. He also associated
phenotype only with the picture of classical model. Due to a lack of complete connection, his
scientific explanation on gene expression in relation to the classical model is superficial.
Compared to the next cases in the integration category, he could not use the molecular model to
elaborate his explanation about expression of dominant and recessive genes.
Interviewer: From these pictures do you think they are related? Teera: These two pictures are the same but they are different nature. This one is two strands of DNA unfolded to polynucleotide two stands. In the process, polynucleotide will be chromatin fiber, chromatid. Chromatid is an arm of chromosome. Chromosome has many sequences that are genes. This picture (B) is a gene that appears in these two chromosomes. … Interviewer: Before this you said ‘A’ is a dominant gene controlling skin or curly hair. How is it related to the gene in this picture or genetic information? Teera: The sequence like this. The top sequence is a base sequence. It is part of a gene. Interviewer: Part of a gene. Teera: Yes, it is a dominant part of the gene. When it is folded, it is a chromosome. Actually, the structure is related to both genes and chromosomes, because genes are on chromosomes. It is like a house of genes.
Interviewer: แลวถาสมมตวาเราดภาพสองภาพนคะ อาจารยคดวาภาพสองภาพนม
ความสมพนธหรอวาเชอมโยงอยางไรคะ Teera: สองภาพนเปนเดยวกนเพยงแควาอยในคนละลกษณะ อนนคอสาย DNA 2 สายทคลออกมาเปนโพลนวคลโอไทด สองสาย และเขาส
กระบวนการสายพอลนวคลโอไทด นกจะพนกนจนกลายเปน โครมาตน
ไฟเบอร โครมาทกส โครมาทกสกจะเปนแขนโครโมโซม ซงแขน
โครโมโซมกจะม ลาดบเบสตางๆ กหมายความวายนในภาพนกคอ ยน
ทมาปรากฏในโครโมโซมสองตวน … Interviewer: กอนหนาทอาจารยบอกวา A เปน gene เดนควบคมผวหรอวาผม
หยกศก และมความสาพนธอยางไรกบ gene ในภาพน หรอวาลาดบ
ของขอมลทางพนธกรรม Teera: ลาดบทเปนอยางน ลาดบดานบนนคอลาดบเบส คอสวนหนงของยน Interviewer: คอสวนหนงของ gene Teera: ใชคอสวนเดนของ gene และพอมนขดพนกนมนกคอโครโมโซม
จรงๆโครงสรางมนกสมพนธกนทง gene และโครงสรางของ
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Interviewer: How about this picture? The gene is what part of chromosome. Teera: The gene is DNA strand coiled into chromosome. Therefore, a gene is in everywhere of chromosome. However, in this picture, the position is this part. Therefore, the expression is related because the picture B is the gene and the picture A is the gene that is trait, phenotype, expressed to one characteristic, such as dominance. … Teera: Genetic inheritance, I gave examples. It has to start from let them know the person who studied is Mendel. He studied 7 traits. What are these traits? For example, height is one trait in seven traits. For tall, representing gene will present with capital letter. They are two characteristics, homozygous dominant and heterozygous dominant. I drew picture for them. Gene expression of dominant genes is always greater than recessive genes. Tall is also the same, but this one is heterozygous. There is a recessive gene in it.
โครโมโซมเพราะวายนกอยบนโครโมโซม เปรยบเสมอนกเหมอนเปน
บานของยน Interviewer: แลวอยางในภาพน gene คอสวนไหนของโครโมโซม Teera: gene คอสาย DNA ทพนเปนโครโมโซม เพราะฉะนน gene กอย
ในโครโมโซมทกสวน เพยงแตวาภาพนมนคอตาแหนงหรอวาชนสวนน ฉะนนการแสดงออกมนกตองเกยวของกนอยแลว เพราะวาในภาพน
(ลาดบเบส)คอยน และภาพน(โครโมโซม)กคอยน เปนลกษณะทเปน phenotype ทแสดงออกมากคอเปนลกษณะหนง เชนลกษณะเดน … Teera: คอการถายทอดลกษณะทางพนธกรรม ผมยกตวอยางขนมา มนกตอง
เรมตงแตใหเขารจกวาใครเปนคนศกษากคอเมนเดล เขาศกษา 7 ลกษณะวามอะไรบาง อยางเชนความสงมนกเปนลกษณะหนงในเจด
เหมอนกน และกความสง โดยสวนมากการแทนยนเขาจะแทนดวย
ตวอกษรตวพพมใหญ กเปนมนกมสองลกษณะกคอ เดนแทกบเดนทาง กเขยนภาพแสดงใหเขาด เพราะอยางไรแลวการแสดงออกของยนเดนก
ตองมากกวายนดอยอยแลว ถาจะแสดงไดกตองมเพยงแคยนดอยอย
ดวยกนเทานน สงเหมอนกนแตวามนสงแบบพนทางซงจะมยนดอยอย
Note. Red text with dotted underline indicates the classical gene model. Blue text with underline indicates the molecular gene model. Bold text indicates coded connection between models.
Uma. Similar to Teera case, Uma provided multiple representations of a gene. She first
said that she was not sure how to draw a picture of genes and then she sketched both a
chromosome and a chemical structure of nucleotide base pair (see Figure 11). Interestingly, Uma
then drew a linked representation of DNA sequence in a chromosome to represent a gene. The
use of the linked representation is a promising case, which could potentially lead to connection
between two models. However, she did not incorporate her idea about a gene as a sequence to
create more coherent connections, and she only stated that the drawing represented the structure
of DNA inside a chromosome. Note that the picture on the right might be a misconception,
confusing the shape of the chromosome with the double helix.
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Figure 11. Uma’s drawing of a gene. This figure illustrates multiple representations of gene.
Interviewer: What cause a genetic disease? Uma: A change of gene location makes the synthesis of blood, enzyme, or hormone abnormally. Moreover, the abnormal trait will be inherited to next generations through chromosomes from parents to offspring (sic.). … Uma: It is very difficult to draw. Interviewer: You can describe what a gene is. Uma: It is just difficult. I don’t know how to draw it. Interviewer: You can explain if you are not sure how to draw it, what it is, where it is. Uma: A gene is located on chromosome. I can draw a chromosome, but for gene. How am I going to draw? Structure? Or shape? Or structure? Interviewer: So it can be many pictures, right? Uma: Yes. It is like. Do you want me to draw a picture or draw a structure? Interviewer: You can start with the one you think it is called gene. So, now you think about the structure one? (Uma was drawing a chromosome.) Uma: Yes. Interviewer: Is this a chromosome?
Interviewer: โรคทางพนธกรรมเกดขนไดอยางไร Uma: การเปลยนแปลงตาแหนงของ gene ทาใหการสรางเลอดหรอ enzyme hormone เนอเยอผดปกต และมการถายทอดลกษณะท
ผดปกตไปยงรนลกหลานโดยผานทาง chromosome ของพอแมส
ลก … Uma: มนคอวาดยากนาดเลย Interviewer: อาจารยอธบายกไดวา gene คออะไร Uma: คอมนยากไมรจะวาดออกมาอยางไร ยากเหมอนกนเนอะ เขยนอธบายก
ไดใชไหม Interviewer: อาจารยชวยอธบายวาทาไมถงวาดไมไดหรอวามนคอวาคออะไร มนอย
ตรงไหนชวยอธบายมากได Uma: gene ทมนอยบนโครโมโซม คราวนตวโครโมโซมวาดไดอยคะ แต
วาตว gene จะใหวาดอยางไรคะ โครงสรางหรอรปราง หรอวาเปน
โครงสราง Interviewer: มนดไดหลากหลายภาพใชไหมคะ Uma: ใชคะ มนจะเปนแบบวา ยงไงอาคะ อยากใหวาดเปนรปวาดหรอวารป
โครงสราง Interviewer: อยางไรกไดอยางทอาจารยคดเลยวา อนไหนทเรยกวา gene คอตอนน
อาจารยคดถงรปโครงสราง
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Uma: Yes. Having the structure, having Mendel’s law. I’m confused. (Uma was drawing a structure of DNA.) Interviewer: You can draft it. This one is the part of DNA? … Uma: I’m not sure. Should I draw a picture? Interviewer: Yes. Can you show me? Uma: If it is a gene. If it is a gene. (She was beginning to draw a new picture of DNA in chromosome.) It has chromosome and DNA. Interviewer: Can you explain what are you drawing? Uma: I linked from this structure that it is inside of chromosome.
Uma: ใชคะ Interviewer: ทมโครโมโซม Uma: ใชคะ มโครงสราง มกฎเมนเดล มอะไร Uma: กเลยแบบ งงๆ Interviewer: อาจารยวาดคราวๆ กไดคะ กดเปนสวนของ DNA เลย … Uma: หรอวาจะใหวาดเปนรปเลย Interviewer: เปนรปกไดคะ รปของอาจารยวาดอยางไรคะ Uma: ถาเปน gene ถาเปน gene
When she explained the pictures given to her in the interview task, she again did not
incorporate her idea about the molecular model to create more coherent connections, even
though the molecular model was prominently presented in other questions throughout the
interview. The excerpt below shows that she demonstrated the partial connection to describe the
relationship between two pictures but that she struggled to elaborate how the DNA double helix
was associated with the nucleotide sequence in the picture B. When she explained the pictures,
she revealed only her ideas about the symbolic classical model, dominant and recessive alleles.
Based on her drawing, her explanation was limited to the DNA double helix structure without
connection to the idea of genes as sequences of instruction.
Interviewer: Do you think these pictures related? Any differences or similarity? Uma: Well. Gene is on chromosome, right? Does it mean alleles? This one is allele. This is on chromosome. Alleles on chromosome.
Interviewer: แลวเหมอนกบอยางสองภาพนอาจารยคดวามนสมพนธกนหรอไม หรอ
วามนมขอเหมอนกนหรอวาแตกตางกนอยางไร Uma: กคอ gene มนอยเปนโครโมโซมอยแลวใชไหมคะ หมายถงอะลนหรอ
เปลาคะ ตวนอยกบอะลนหรอวาตวนจะอยกบโครโมโซม กคออะลนอย
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c) Integration. The previous cases show that most teachers conceptualized genes with
multiple models; however, they applied them separately and incoherently. Although they were
more or less able to make certain structural connections between the two models, they struggled
to relate the two models functionally and to explain the function of a gene in the molecular terms
of protein expression. The results show that only a small number of teachers integrated the
classical and molecular models to in their scientific explanation. TR5-Nampen and TR6-Pakorn
were promising cases who applied multiple models coherently and meaningfully beyond the
partial connection. The common themes that emerged from cases coded in the integration
category were:
a) the classical and molecular models were applied concurrently in a single explanation;
b) explicit connections of biological structure between the two models were constructed;
c) functions of both models complemented each other to explain genetic phenomena;
d) both models were situated in real genetic contexts.
Interviewer: You can do like you explaining students. Uma: This point, right? It is on each side of chromosome. When chromosome pair up together, there are some points can build some traits. This point is called allele. They always have to be in a pair. There are dominant allele here and recessive allele on this one. … (talking about picture A) Uma: This one is chromosome. It has traits. And having DNA. Connecting until there is a gene inside here. Interviewer: Do you think students will be able to make connection? Uma: Yes, they understand. But, is this one helix DNA, right? It should be helix DNA.
บนโครโมโซม Interviewer: เหมอนกบอาจารยอธบายนกเรยนกไดคะ Uma: จดอนนใชไหมคะ มนจะสรางอยบนโครโมโซมแตละขาง และตอนท
โครโมโซมแตละขางมนจบเขาคกนมนกจะมจดทสรางลกษณะบาง
ลกษณะ ไอจดอนนนเราเรยกวาอะลน มนตองจบคกนเสมอคะ กมยน
เดนตรงนกบยนดอยดานนคะ
… Uma: อนนคอโครโมโซมมนจะมลกษณะของมนและกจะมสาย DNA เชอมๆ กนมาและมลกษณะของ gene ทอยตรงนอาคะ Interviewer: โอเคเขาใจแลว ขอบคณมากคะอาจารย คาถามสดทายคอ แลวสมมตวา
ถานกเรยนเขาสามารถสรางความเชอมโยงระหวางสองภาพนไดไหมคะ Uma: เขากเขาใจนะคะ แตวาอนนมนกเปนสายเปนเกรยว DNA ถกไหมคะ
มนเปนเกรยว DNA
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Nampen. When Nampen described how she taught classical genetics in conjunction with
molecular genetics, she demonstrated complete connection between classical and molecular
models. First, she discussed the function of each model consecutively and demonstrated partial
connection by explaining the structure of genes, DNA, and chromosomes. With the classical
model, she first discussed the effect of different versions of alleles on phenotypes. With the
molecular model, she discussed the effect of different protein sequences on gene expression.
This revealed her cognitive knowledge on the structure of genes.
Then, Nampen applied both models in integration to elaborate why a sickle cell anemia is
called a genetic disease. She integrated the classical model and the molecular model in such a
way as to enhance functions of each model in controlling sickle cell anemia. Unlike the teachers
from separation and partial connection categories, she coherently addressed functions of the
gene, both ‘genetic inheritance’ and ‘gene expression’, in one explanatory domain, rather than
separating the models into the classical and molecular domains. She applied both models in one
context to explain a genetic phenomenon of sickle cell anemia. This revealed her strategic
knowledge of applying multiple models of genes in connection.
To illustrate the integration, I interpreted her explanation and coded the associated gene
function.
Nampen: a) If we take a look at protein strands of red blood cells of normal people and patients. Look at their proteins. Are they the same? Students will say ‘No’. Some locations have different types of amino acids, different sequences. b) People with different genotypes will pass different genes to offspring. We will link. Therefore, sickle cell anemia can be transferred. I will point that it is genetic disease and it can be transferred. c) This genetic inheritance leads to building abnormal protein and changed shape of blood cells. a) Patients have a different protein sequence from normal individuals (gene expression).
b) Patients pass a different version of a gene to offspring (genetic inheritance).
c) Offspring has abnormal proteins due to that inherited gene (gene expression).
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Interviewer: …How do you connect these two chapters (classical genetics and molecular genetics)? From students’ understanding about a gene to a gene inside DNA. Nampen: How to link from a gene to DNA, right? Starting from students learn about probability, calculation, based on Mendel’s laws. Then, connecting to show that on chromosome (sics). I will use this picture. Showing the picture first. From what we learn. We learn about the gene. Representing the gene with alphabets. Upper-case letter is dominant gene controlling the expression of dominant trait. And, lower-case letter controls the expression of recessive trait. They work together. In fact, when we look under microscope, we will not see alphabets like A, B, C. This is just an assumption by considering the location of genetic material on chromosomes. Then I link pictures like. Like. Ask students to look. This is a cell, right? This part is nucleus of cells. We learn what is in nucleus. Cell division, right? We also learned about karyotypes. If we stretch this out, it will compose of chromosome. We will see it during the cell division. If we uncoil, we will see chromosomes have strands of genetic materials, called DNA. Long strand. And proteins help in forming chromosome. Therefore, chromosomes consist of DNA, genetic materials. Some parts of DNA control traits. This part of DNA controls what trait. That means gene is a unit to control trait. Therefore, three words, 1. Chromosome, 2. DNA, 3. Gene. Which location controls what trait, we need to keep study. …Then we connect to protein synthesis right? We may use picture from IPST. Like that. It will be pictures of red blood cell of sickle cell, right? That one is ok. That one will be easy. This is the picture of red blood cell of normal people. This is from patient with the disease. Look at the red blood cells. How are they different? What is the function of red blood cell? What will happen if the shape of red blood cell is changed? What you think will be wrong? What will happen to people who have sickle cell anemia? I will like to like this. I will not say this is abnormal. I will ask them to think and link to function. Then, I will tell them that red blood cell consists of proteins. If we take a look at protein strands of red blood cells of normal
Interviewer: …อาจารยเชอมโยงระหวางเนอหาสองบทนอยางไรคะ จากความรของ
นกเรยนในเรองยนไปสยนในดเอนเอ
Nampen: วาจะเชอมโยงมาทยนหรอ DNA ถกไหมคะ กตองวาจากทนกเรยนได
เรยนมาเปนเกยวกบดหลกความนาจะเปนการคานวณซงสอดคลองไป
ตามกฎของเมนเดล แลวกเชอมโยงใหเหนวาบนโครโมโซม ใชภาพน
ประกอบ คอตองดงภาพใหเหนกอน จากทเราเรยนกน เรากเรยน
เกยวกบยน แทนยนดวยตวอกษร เปนตวอกษรตวใหญกจะเปนยนเดนท
ควบคมการแสดงออกของลกษณะเดน แลวอกษรตวเลกยนดอยควบคม
การแสดงออกของลกษณะดอย แลวกทางานรวมกน แตในความเปนจรง
แลวเวลาทเรามาศกษาดในกลองจลทรรศนจรงๆ เราไมเหนเปนตวอกษร เปน A B C อนนเปนการสมมตขนโดยพจารณาตาแหนงของสาร
พนธกรรมทประกอบอยบนโครโมโซม แลวกเชอมภาพน ถามวาเชอม ประมาณนคะ กคอแบบน เอาเขามา บอก
นกเรยนด อนนคอเซลลถกไหม สวนนกจะเปนนวเคลยสของเซลล ใน
นวเคลยสเราเรยนมาแลว แบงเซลลถกไหมคะ แลวกเรยนการจดทาคาล
โอไทดมาหมดแลว เพราะฉะนนถาดงออกมา ในนกจะประกอบไปดวย
มโครโมโซมประกอบอย ซงเราจะเหนชดเจนในระยะอยางนไดกคอชวง
ทเซลลมนกาลงจะเกดการแบงตว ถาเราขยายคลายเกลยวออกมา เรากจะ
พบวาโครโมโซมประกอบไปดวยสายของสารพนธกรรมทเราเรยกวา DNA ประกอบกนเปนสายยาว แลวกมโปรตนพวก เปนตวชวยขดให
กลายเปนแทงแบบน เพราะฉะนนอนนคอโครโมโซม โครโมโซม
ประกอบไปดวย DNA ซงเปนตวสารพนธกรรม DNA บางชวงบาง
ตาแหนง ตาแหนงนคมลกษณะน ตาแหนงของ DNA ทคมลกษณะ
ไหน นนกคอการกาหนดวาเปนยนทควบคมแตละลกษณะ เพราะฉะนน 3 คากคอ 1.โครโมโซม 2.DNA 3.ยน เรากจะดงตรงน ทนแลว
ตาแหนงไหนบาง อะไรกาหนดอยางไรบางกเดยวเราตองเรยนรตอไป … แลวเราจะตองเชอมโยงไปถงการสงเคราะหโปรตนใชไหมคะ ก
อาจจะใชเปนภาพจาก สสวท. กได ประมาณแนวนน กจะเปนภาพของ
เซลลเมดเลอดแดงทเปนซกเกลเซลลใชไหมคะ อนนนกได อนนนก
งายๆ อนนคอภาพเซลลเมดเลอดแดงของคนปกต อนนคอภาพของ
ผปวยทเปนโรคน ดสลกษณะเซลลเมดเลอดแดงตางกนยงไง แลวเซลล
เมดเลอดแดงทาหนาทอะไร ถารปรางมนผดปกตไปแลว หนคดวาจะ
เกดความผดปกตยงไง เพราะคนทมอาการในกลมอาการของซกเกล
เซลลตรงนจะเปนอยางไร คอจะโยงมาอยางน จะไมไดบอกวานผดปกต
แลวจะ คอใหเขาลองคดเชอมโยงกบหนาท พอเสรจเรยบรอยกบอกวา
จรงๆ แลวเซลลเมดเลอดแดงมนประกอบไปดวยโปรตน มาวเคราะหด
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people and patients. Look at their proteins. Are they the same? Students will say ‘No’ U. USome locations have different types of amino acids, different sequences. UPeople with different genotypes will pass different genes to offspring. We will link. Therefore, sickle cell anemia can be transferred. I will point that it is genetic disease and it can be transferred. This genetic inheritance Uleads to building abnormal protein and changed shape of blood cells. UTherefore, this is one point to link for students that UDNA is related to protein synthesisU. DNA is genetic material. Our body is composed of many proteins. We said some proteins are for energy. Some proteins are for function as composition of our body. Do you understand? Therefore, our traits are controlled and transferred by genetic. UProtein synthesis is controlled by genetic materialU. (Then, Nampen talked about mechanisms of protein synthesis in detail.)
สายของโปรตนทเปนองคประกอบของเซลลเมดเลอดแดงของคนปกต
เทยบกบคนทเปนโรค ดสสายของโปรตนเหมอนกนไหม เดกกจะบอก
วาไมเหมอนกน มบางตาแหนงทมชนดของกรดอะมโนทเปน
องคประกอบในสายโปรตนตางกน ลาดบตางกน เรากเชอมโยง คนทมจ
โนไทปตางกนจะสงผานยนตางกน เพราะฉะนนซกเกลเซลลอะนเมย
เปนโรคทสามารถถายทอด เพอชใหเหนวาตรงนเปนโรคทางพนธกรรม มนเปนโรคทถายทอดทางพนธกรรมได และการถายทอดทางพนธกรรม
ตรงนมนมผลทาใหสายของโปรตนทสรางขนผดปกตและรปรางของ
เซลลเมดเลอดผดปกต เพราะฉะนนอนนเปนจดนงทเชอมโยงใหเดกเหน
วา DNA มนนาจะเปนในเรองของการสงเคราะหโปรตน ดเอนเอเปน
สารพนธกรรม เพราะฉะนนรางกายของคนเรากประกอบไปดวยโปรตน
เยอะแยะไปหมดนะคะ และเรากบอกวาเหมอนกบโปรตนบางสวนก
อาจจะมการนาไปสลายพลงงาน …บางสวนสงมาควบคมเปน
สวนประกอบตางๆ ของรางกาย นองพอเขาใจมย แลวเรากเชอมโยงใหเหนวา เนยเพราะฉะนน ลกษณะตางๆของเรา พนธกรรมเปนตวกาหนดและสงผาน กระบวนการสงเคราะหโปรตนก
คอกาหนดดวยสารพนธกรรม Note. Red text with dotted underline indicates the classical gene model. Blue text with underline indicates the molecular gene model. Bold text indicates coded connection between models.
During the multiple cards task, Nampen discussed in detail how a double helix DNA
strand related to alleles in chromosomes. She pointed out that students and teachers could have
misconceptions that the upper stand of DNA represents one allele and the lower stand represents
another allele. In fact, one allele refers to a section of nucleotide sequence of both stands of a
double helix DNA. This problem is a result of the lack of integrated connection between two
models. With the established connection, one could explain that allele ‘R’ and allele ‘r’ have
different sequences. Nampen was able to make an explicit connection that a gene sequence in the
picture B could be either section ‘R’ or section ‘r’ of chromosomes in the picture A depending
on an instruction of the sequence. Compared with teachers coded in the partial connection
category, Nampen explicitly linked the symbolic classical model (alleles) and the molecular
model.
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Furthermore, she pointed out the classical conception of the gene is limited to a simple
genetic trait. She elaborated that in fact most genetic traits are controlled by non-Mendelian
inheritance patterns such as linked genes. She pointed out that the picture A of highlighted alleles
on homologous chromosomes does not fully explain the location of a gene in non-Mendelian
inheritance traits.
Interviewer: How do you think these pictures are related? Nampen: Picture A shows chromosome. Chromosome composes of DNA, DNA strand. Therefore, location, location of Umm capital R and small r represent the location of a gene. Section of DNA that controls a trait. Therefore, picture B, picture B is. Representing sequence in DNA strand, double helix. When we unfold to double helix and this (picture A) is the location of a gene. If you ask how to connect. A word gene here. From my understanding, R is the location of this gene (picture B). Right? Can you tell me the answer? … Interviewer: Do you think students can make connection between these pictures? Nampen: Like I said, using animation and representations could help. Using these to evaluate student understanding. Students may understand that this (upper strand of DNA) is one (R chromosome) and this (lower strand of DNA) is one (r chromosome). Actually it is another one. This is not correct, because this is chromosome. Chromosome composes of double strand of DNA and gene. These pictures also can use for evaluation. Students always think capital ‘R’ is this one strand of DNA and ‘r’ is its’ matching like this. This is misconception. Not only students, teachers also have misunderstanding. This is gene as location. This is homologous chromosome which is a pair from rearranging. If students confuse, we need to talk and connect to help them understand. Connecting to what they learn like cell division. … Nampen: You already did this, Karyotype. These are homologous chromosome. If you unfold it will be
Interviewer: อาจารยคดวาสองภาพนมความสมพนธกนอยางไร Nampen: รปเอ แสดงถงโครโมโซม บนโครโมโซมประกอบไปดวยดเอนเอ สาย
ของดเอนเอ เพราะฉะนน ตาแหนง ตาแหนงของ เออ R ใหญ และ r เลก ทแสดง กคอตาแหนงของยน ตาแหนงของชวง ของดเอนเอท
ควบคมลกษณะ เพราะฉะนนถารปบ รปบนะคอ แสดงลาดบเบส ใน
สายของดเอนเอทเปน double helix แตพอคลออกมาเปนสายค แลว
กตาแหนงนกคอยน เพราะฉะนนถามวาเชอมโยงอยางไร คาวายนในทน ในทเขาใจกคอสวนทเปน R กคอตาแหนงของยน ถกมยนอง เฉลยให
ฟงหนอย … Interviewer: อาจารยคดวานกเรยนมความเขาใจเชอมโยงสองภาพนหรอไม
Nampen: กใชอยางทบอก คอ animation กบภาพประกอบกนาจะเขาใจได ก
ใชในการประเมนการเขาใจได เดกบางคนจะเขาใจวาอนนกคอ หนงอน อนนกคอหนงอน จรงๆแลวมนไมใช เพราะอนนคอโครโมโซม แลว
โครโมโซมประกอบไปดวยดเอนเอทมนเปนสายค และกยนอยางน เพราะฉะนนรปนกจะใชประเมนได เดกกมกจะคดวา R ใหญกคออนน
รเปลาอาจารย และ r เลกกคอมนมาคกนอยางน อนนคอการเขาใจผด
คอ misconcept อยาวาแตเดกเลย พวกอาจารยเองกยงเขาใจกนผด
อยเลย อนนกคอยนเปนตาแหนง อนนกคอโฮโมโลกสโครโมโซม กคอ
เปนโครโมโซมคเหมอนทเกดจากการจดเรยง ถาเดกเคาสบสนกอาจจะ
ตองมาคยและเชอมโยงใหนกเรยนเขาใจ และเหน มนเปนปญหาหลก อะ เชอมโยงอะไรบางกทนกเรยนเรยนมาแลวเรองการแบงเซลล … Nampen: อะทหนทามาแลว เตรยม karyotype กอนหนาน แลวอนนเปน
โครโมโซมทคเหมอนกน จบคกบภาพเมอกน อนนทคลออกมามนกคอ
สายดเอนเอนนแหละ สาย เพราะฉะนนชวงของดเอนเอคอตาแหนงของ
ยน เพยงแตวาอะอนนตาแหนงน เปน R r แลวถาเราบอกไปตามกฎ
ของเมนเดลเนยเคากบอกวายนมนตองอยแยกกน เออ มนไมม linked
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DNA. Therefore, a section of DNA is location of gene. Just that this location is R, r. If we tell based on Mendel’s laws, he said genes are separate. Umm. There is no linked gene. However, in fact there are many genes that may be linked on one chromosome. Based on Mendel’s law, one gene is one coordinates on chromosome. Independent assortment can occur. Students confuse about this. If fact, there are also linked gene. … Nampen: I would like to ask for these materials. Can I use it to clear student misunderstanding? I think it will be good if we ask what a gene is. Asking what this picture is, and how about this. Then asking them to draw a picture of gene base on their understanding. This would be good.
gene กฏของเมนเดลแตในความเปนจรงยนมนกมเยอะมนอาจจะ link อยบน โครโมโซมเดยวกน แตถาตาม กฏของเมนเดลยนหนง
ตาแหนง หนงยนกคอพกดบนโครโมโซม ดงนนมนกเลอกไดอยาง
อสระ เดกมกจะสบสนตรงน ในความเปนจรงนจะม link gene อก … Nampen: อาจารยอยากจะขอภาพสออนนไปใช จะไดเคลยรความเขาใจของเดก พคดวาถาจะใหด ถาถามวายนคออะไร แลวเดกกบอกวา ภาพนคออะไร ภาพนคออะไร แลวพอเสรจสนแลวคอยใหวาดยน
ออกมาตามความเขาใจ คดวานาจะด
Pakorn. Pakorn is another case that applied multiple gene models coherently and
meaningfully. He revealed his integration of the two models when he talked about students’
difficulty in learning genetics. He found that students’ main difficulty was a lack of
understanding of underlying molecular processes that account for dominant or recessive alleles
in classical model. In other words, students could not make coherent connections between the
classical model and the molecular model.
Pakorn’s response clearly shows that both models appeared in integration in a single
concurrent explanation: he used both models in the same places, switching back and forth
between them. He applied both models to describe how genes lead to a variation of colors in a
genetic trait. Interestingly, Pakorn identified phenotype with the classical model (A and a) and
applied the molecular model to elaborate molecular processes underlying gene expression of the
classical models. Therefore, his explanation was completed by the integration of multiple models
in terms of both structure and function. Unlike Nampen, Pakorn used the simple language that
many of the teachers can use to talk about the separate models.
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Interviewer: From your teaching experience, how student understand about structure and function of the gene? Do they have any problems? Pakorn: How could it be the same characteristic? It is white and black. We have to say a characteristic is color. A color trait is very; there are black and white. … Pakorn: White and black. What are differences? If it is big ‘A’, nucleotide sequence would be different from small ‘a’. If nucleotide sequence is not the same, synthesis process will give different substance. Yes. The sequences of nucleotides are different. … Pakorn: They don’t understand. They do not link this part. If we tell dominant gene and recessive gene and we do not connect why this called dominant and why this called recessive. Interviewer: Why dominant or recessive? Pakorn: If it is dominant, it builds another substance. If it is recessive, it builds another substance. Each substance has different characteristics.
Interviewer: แลวอยางทอาจารยสอนมา จากประสบการณของอาจารย นกเรยนเขาม
ความเขาใจเกยวกบเรองโครงสรางหรอวาเรองหนาทของยน เปนยงไง
บาง มปญหาอะไรบางหรอเปลาคะ
Pakorn: ลกษณะเดยวกนไดยงไง เพราะวามนสขาวกบสดา เราตองบอกคาวา ลกษณะกคอสไง ลกษณะของส มนก Very คาวาเปนสขาวกบสดา … Pakorn: เออ สขาวกบสดา แลวมนตางกนยงไง ผมก เอะ ถามนเปน A ใหญ ลาดบ Nucleotide มนยอมไมเหมอนกบ a เลก เมอลาดบ Nucleotide ตรงนไมเหมอนกน เวลามนไปสงเคราะหสาร มนกยอม
ไดสารทมนตางกน ใชมนเปนลาดบของ nucleotides ทตางกน
… Pakorn: เคาไมเขาใจ เคายงไมเชอมโยงสวนนเลย กคอถาเราบอกวาเรอง Gene เดนกบ Gene ดอย ไมเชอมโยงกลบไปวา เอย ทาไมมนถงเดน ทาไม
มนถงดอย Interviewer: ทาไมมนถงเดน ทาไมมนถงดอย Pakorn: เพราะวาถามนเดน มนสรางสารไดอกตวหนง ถามนดอยมนกตองสราง
สารอกตวหนง สารคนละตวทมคณสมบตทตางกน
Note. Red text with dotted underline indicates the classical gene model. Blue text with underline indicates the molecular gene model. Bold text indicates coded connection between models.
To elaborate, in order to understand the function of dominant/recessive alleles students
need to understand the underlying processes: how genetic elements are inherited through meiosis
and mating, and how these elements act to cause the phenotypic differences. Redfield (2012)
explained that these processes were treated as ‘black boxes’ by geneticists (and in the curricula)
and students appeared to avoid this challenge by simply memorizing the rules and definitions
given by teachers without understanding the underlying processes. This also confirmed that Thai
teachers found a lack of connection between multiple models of the gene as a learning problem
in Thai classrooms.
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Pakorn added that he always asked questions to help students link main concepts. The
following excerpt reveals the application of multiple models to explain genetic phenomena. To
explain the differentiation of cells—in other words, how the gene expression leads to various
structures of cells—he applied the classical model according to which genes in chromosomes of
all cells are the same due to mitosis division. Although this statement did not clearly state two
models of the gene, the explanation required both models in order to fully understand cell
differentiation phenomena.
Pakorn: Sometimes I asked why cells at little fingers and cells at a nose have the same chromosomes. Students will not get this. To explain this, students need to connect the topic about cell division. OK. If it is mitosis, we have to point out that mitosis creates cells that are the same in all aspects. The body is from Mitosis cell division. It is the fact that cells will look the same. I try to link every topic together.
Pakorn: แลวแตๆ บางครงบอกวา เคยถามวา เอย Cell ทปลายนวกอยกบ Cell ทปลายจมก ม Chromosome เหมอนกน เดกกไมคอยจะ Get นะ การทจะไปอธบายเรองนไดมนกๆ ตองไปเชอมโยงๆ เรอง
ของการแบง Cell โอเค ถามนเปนการแบงแบบ Mitosis เราตองย า
วา เออ มนเปน Mitosis พอมนเปน Mitosis กคอเหมอนเดมทก
ประการ เหนวารางกายมนเกดจากการแบงแบบ Mitosis ตองยอมรบ
วามนเหมอนกนทกประการ คอเชอมโยงทกเรอง
Similar to Nampen, during the multiple cards task Pakorn demonstrated explicit
connection between the symbolic classical model and DNA molecule of the molecular model. He
also stated the same possible misconception that students may think the upper stand of DNA
represents one allele and the lower stand represents another allele. The analysis also reveals a
meta-level understanding of the models; he thought that multiple representations of genes have
different purposes. Picture A of the classical model illustrated the location of the gene and the
picture B was used to describe the function of the gene in controlling a sequence of amino acids.
Pakorn: I think if we compare picture A and B together, we may link directly to this one ‘R’. Interviewer: Instead of writing just ‘gene’ Pakorn: Otherwise, students will understand that ‘R’ is this side (upper strand) and r is this side (lower strand),
Pakorn: คดวาเราเอาภาพเอกบภาพบมาคกน กอาจจะโยงมาเลยวาตวนคอ R Interviewer: แทนทจะเขยนวาแค gene Pakorn: มเชนนนแลวเดยวเดกจะเขาใจวาอกกรณหนงนะ ถาอยางนนเดกกจะ
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which is wrong concept. If it is r, it need another strand (DNA molecule). Interviewer: Yes. Pakorn: If we link this is ‘R’ (picture B) and this one is ‘R’ (picture A), student will understand ‘R’ is this one. Where is ‘r’? It is not the opposite strand, because ‘r’ needs another strand. We can link from here to here. This point is ‘R’, and this point is ‘r’. For me, I think this will help link between two pictures. If this is ‘R’ (using word ‘R’ instead of ‘gene’ in the picture B). … Pakorn: Sometime, look at the content. Look at the molecular structure. At least they understand. If they look over, is this side ‘R’? or this side ‘r’? When students do not ask, we also forget to tell them, because, we think they will understand. Both A and B describe what is a gene. A can be used to explain the location of a gene. B can be used to explain about function of the gene, right? If we explain function about codon. Codon controls sequence of amino acids. I think this activity is a good one. Then, continuing steps by steps.
เขาใจวาฝงนคอ R ฝงนคอ r ซงมนกผด ถามนเปน r มนตองมอกเสน
หนง Interviewer: ใชคะ Pakorn: ถาเราโยงวาตรงนคอ R ตรงนคอ R เดกกจะเขาใจวา R คอตรงนนะ r อยไหน r ไมใชฝงตรงขามเพราะวา r กตองมอกเสนหนง อาจจะโยง
จากนมาน ตรงนคอ R นะ ตรงนคอ r นะสาหรบผมนะ อยางนมนกด
เชอมโยงระหวางสองรป ถาเปน R ตรงนนะ … Pakorn: บางทกดจากสาระ ดจากโครงสรางโมเลกล อยางนอยเขาจะไดเขาใจ อยางถาดผานๆ ฝงน R หรอเปลา หรอวาฝงน r พอเดกไมถามเรากลม
บอกเพราะเราคดวาเขาเขาใจ ทง เอ และ บ อธบายวา gene คออะไร เอ นาจะอธบายถงตาแหนง
ของ gene ได บ กอธบายถงหนาทของ gene ไดใชไหม แตถาเรา
อธบายหนาทกคอเรองของโคดอน โคดอนควบคมลาดบของกรดอะม
โน อาจจะ ตรงนผมวาเปนกจกรรมทดแลวคอยๆ ไลสเตป
Cross-Case Analysis of Teachers’ Conceptions of Multiple Models of Genes
A cross-case analysis explores a relationship between teachers’ default ideas about the
gene and the levels of connections between multiple models (see Figure 12). The circle
represents a teacher coded in the categories. The left side represents the teachers in a classical
model group (those who preferred the classical model in their initial explanations) and the right
side represents the teachers in a molecular model group (those who preferred the molecular
model). The Y axis refers to the level of connections between the models, from separation to
integration, which the teachers constructed during the interviews. For example, the circles
indicating TB5 and TB6 represent two teachers coded to the same degree, within the molecular
model group and the integration level.
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Figure 12. Cross-Case Analysis of Teachers’ Conception of Multiple Models of Genes. The
circle represents teacher participants.
The cross-case analysis shows that about 67 percent of participants developed a partial
connection. The teachers in this level understood how the molecular model complements the
classical model but applied them separately. In the classical model group, no teachers were able
to make the integration between two models and about 17 percent of participants conceptualized
the two models in separation. In the molecular model group, about 17 percent of participants
applied the models in integration by using them to solve one particular genetic phenomenon.
This significantly demonstrates that the teachers who developed the molecular model as their
default model for explaining a gene demonstrated better connections between the classical model
and the molecular model. Therefore, the results confirm that having a complete understanding of
the molecular model is the basis for applying multiple models in integration. The unanswered
Inte
grat
ion
Part
ial
Con
nect
ion
Sepa
ratio
n O
ne M
odel
- Constructing multiple models - Connecting multiple models - Applying multiple models in integration - Situating multiple models to explain a phenomenon
- Constructing multiple models - Connecting multiple models - Applying multiple models in separation
- Constructing multiple models - Applying multiple models in separation
- Developing a particular model - Not applying an appropriate model in contexts
TB5 TB6
Classical Model Molecular Model
TB4 TR2
TR1 TR5 TR6 TB1 TB2 TB3 TR3 TR4
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questions are whether the salient model remains the predominant model in teaching and how
teachers balance multiple models in their explanation for learners.
The analysis reveals that the meaningful integration was demonstrated within the situated
contexts of genetic phenomena. Within the partial connection category, the teachers only made
connections centered on the biological structure of genetic material: this only required an
understanding of the gene model in a cognitive domain. Their explanations were not associated
with genetic phenomena or particular functions of the gene. Full integration, on the other hand,
requires both a conceptual knowledge about the structure of genetic material and a strategic
knowledge of how to apply both models to explain scientific explanation in integration.
Compared to students, who were the focus of my master’s thesis, the teachers made more
sophisticated and integrated connections. Most students in that study failed to draw accurate
connections between multiple models, when they made any connections at all; they tended to
apply models in separation. This analysis can also be used to interpret the learning progression of
teachers regarding multiple models of the gene. The level of expertise in genetic content
knowledge allows teachers to develop a sophisticated understanding about the connection
between genetic structure and function. Authentic genetic problems, however, are not separated
into discrete categories of genetic inheritance and gene expression, as in the curriculum. To fully
explain genetic traits in nature, a teacher need to understand the underlying connections and be
able to apply multiple models of the gene interchangeably
Moreover, some teachers commented that a lack of meaningful connection is also a
problem among teachers. Montana stated that “Actually, teachers also have this problem. We
don’t know how to count it as one gene. We need to know the relationship between these
pictures [from the interview questions]. A teacher also wants a learning material like this one”.
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Malee, Sukan, and Atita also added that they have never thought about different types of models
in the gene concept. They agreed that the current instruction did not address multiple models
meaningfully, and Malee said she did not teach how the sequence of instruction is related to
difference in alleles.
Teachers’ Pedagogical Content Knowledge
In addition to teachers’ content knowledge, this study explored teachers’ pedagogical
content knowledge regarding students learning and instructional strategies, specifically in
genetics topic. A primary goal was to gather teachers’ ideas for continuously developing the
designed learning materials; their insights about teaching genetics were used to inform the
modification on materials, as discussed in detail in Chapter 5. However, the analysis revealed
that, due to various factors, the collected data concerning PCK from this project is not enough to
draw a conclusion about teachers’ PCK on teaching genetics. Regardless of limited data on PCK,
I will discuss (a) teachers’ beliefs about students’ learning of genetics and (b) teachers’ beliefs
about teaching classical and molecular genetics, to illustrate some examples of the findings from
this study. These findings could be useful guidelines for future research and professional
development.
The main factor influencing limited PCK data was that an idea about a scientific model
was a new idea for the teacher participants. Although some teachers reported that they found a
challenge in learning the gene concept among students in their classrooms, they did not aware
that multiple models are presented in the curricula and disconnected presentation of the models
could play a role on students’ difficulty. In the workshop, the teachers also were asked to modify
the designed learning materials aiming for connecting multiple gene models. This task requires a
particular teaching repertoire of aforementioned targeted learning outcome; in other words, the
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teachers need to have knowledge of both models in integration and expertise in pedagogies for
connecting the models. Since the topic was considerably unfamiliar for the teachers, without
expertise in the topic they could not deliberate a rich explanation of how to alleviate this
challenge. Furthermore, it is difficult to scaffold PCK development in teachers and to assess it
once constructed (Magnusson et al., 1999) because teachers do not consciously used PCK when
planning lesson (Kind, 2009). The interview questions need to be redesigned and specifically
tailored to document elements of teachers’ PCK in more detail.
Teachers’ beliefs about students’ learning of genetics. In the workshop, the teachers
discussed about students’ conceptions and students’ difficulties in learning genetics around the
gene concept. For instance, the teachers responded to the questions: In your teaching experience,
what do your students typically know about the gene? What are students’ difficulties in genetics
you found in your classroom? Can you provide some examples of instructional strategies to
remedy the problems?
Regarding students’ conception of the gene, the analysis showed that most teachers
believed their students would describe a gene using the classical model, mostly as a passive
particle. This response was corresponding with the findings from the previous studies that most
high school students viewed genes as particles (Auckaraaree, 2009; Venville & Treagust, 1998).
When the teachers described the importance of learning genetics, half of the teachers believed
that an understanding of the molecular model on biotechnology and genetics in everyday life.
Another group of teachers place the emphasis toward the application of classical genetic
knowledge for transmission of genetic disease and couple selection. This showed that, from
teachers’ perspectives, what important for students in learning genetics is contradicted to what
student learned in biology courses.
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Moreover, the analysis on teachers’ believes about student difficulties confirmed the
reviewed problematic issues in high school genetics that should be address in designing learning
materials. The teachers reported that challenges in learning genetics are due to the following
factors: (a) abstract nature of gene concept; (b) lack of knowledge about the molecular model’
(c) lack of connections between models; (d) and lack of connections among genes, proteins, and
phenotype. Excerpts below are examples of teachers’ responses to students’ difficulties.
a) Abstract nature of gene concept Interviewer: What do you think students’ answers on what a gene is will be? Malee: What a gene is. A gene is a unit of genetic inheritance transferred from generations. Some students will say a gene is ‘A’, a gene is ‘B’, a gene is a dot, a gene is a circle. They say a gene that is invisible is a control unit. Since we cannot see it, teaching about it is an assumption. Assuming that a shape of a gene is like this. Some people use ‘A’, ‘B’, dot, or circle. This is difficult for students to know. It could be anything because it is symbol representing what we called genotype. We have to understand that genotype is invisible depending on how who view it. It is not wrong because they use ‘A’ as symbol of genes. Representation of thing we teach.
Interviewer: จากประสบการณของอาจารย gene คออะไรตามความเขาใจ Malee: gene คออะไร gene กคอหนวยควบคมระดบทางพนธกรรม
ถายทอดจากรนสรน บางคนกบอกวา gene คอเอ gene คอบ gene คอจดกลม gene คอวงกลม และบอกวา gene ทเรามองไม
เหนเปนหนวยหนงทควบคมไป เพราะฉะนนถามองอยางนปป ลกษณะ
การเรยนมการสมมต สมมตฐานรปลกษณวา gene นาจะมรปรางแบบ
นนะ บางคนใหเปนเอ บางคนใหเปนตวบ บางคนใหเปนจดกลมๆ บาง บางคนใหจดกลมทบบาง มนอยากทนกเรยนจะเขาใจ มนกไดทงนน
เพราะเปนรปลกษณแทนตวทเรยกวา genotype ตองเขาใจวา genotype เรามองไมเหนกระจายอยไปหมดแลวแตใครจะมอง บาง
คน gene คอเอ กไมผดเพราะวาเขาใหตวเอเปนรปลกษณแทน gene เปนรปลกษณแทนสงทสอน
b) Lack of knowledge about the molecular model and d) and lack of connections among genes, proteins, and phenotype Interviewer: Could you please explain more about linking proteins to observed characteristic, and from changed gene sequence? How do students face difficulty? Atita: Students do not see the relationship how gene impact. I talked about how a protein is changed based on sequences, such as hemoglobin. There is a mutation in structure, so it is changed. What is the function of hemoglobin? It makes symptom. It makes abnormality. I just explain continuously. Sometimes, students do not have strong background on DNA structure or gene structure.
Interviewer: ชวยอธบายเพมเตมสวน ทอาจารยบอกวาเชอมโยงลกษณะโปรตนหรอ
วาภายนอกอยางไร จากลาดบยนทมนเปลยนไป นกเรยนเขามปญหา
อยางไรคะ Atita: นกเรยนเขาไมเหนความสมพนธวายนสงผลมายงไง กคอพดถงเรองของ
กรณทวาโปรตนมนถก มาแปลงมาเปนลาดบของตวนกคอเปนอะไรนะ เปนฮโมโกบนอะไรอยางน เพราะฉะนนตวนมนผดไป โครงสรางตวนก
เลยผด และตวนฮโมโกบนทาหนาทอะไร มนกเลยทาใหอาการมนกคอ
ผดปกต เรากอธบายไปเรอยๆ บางครงนกเรยนเคายงไมแนนพอเลยวา
โครงสรางของดเอน หรอโครงสรางยนมนเปนยงไง
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c) Lack of connections between models Interviewer: You mean these chapters are about the same topic. Kanisha: Yes, they are about genetic traits. When students read it is calculation and then it is end. Then, it is very chemistry. Enzyme something like that. That’s why students separate to two chapters by themselves. We did not say they are separate. They are connected. When they see questions that are linked. The big question talks about population and then link to DNA to translation. Students were confused. Oh, they are not two topic and they were blank. In the exam room, those parts were gone. Like that. Interviewer: Can you explain further? Kanisha: It is like there are some practices and some exams begin that there is genotype like this. The question is if genotype is like this, what trait is controlled. There are these many proteins. In this type of genotype, the question is what the sequence is. Like this, students will ask what, confused, cannot link. That question will be ruined.
Interviewer: อาจารยหมายถงวาสองบทนความจรงมนคอเปนเรองเดยวกน Kanisha: ใช มนเปนเรองลกษณะทางพนธกรรม แตวาเขามาอานกเรองการ
คานวณแลวจบไปแลว มาถงมาเปนเคมจา เอนไซมอะไรอยางน โครงสราง ทาใหเดกเขาตแยกเปนสองบทดวยตวเอง ทงๆ ทเราไมได
บอกวามนแยกนะ มนเชอมโยงกนนะ พอไปเจอโจทยทมนเชอมกน
โจทยขอใหญทพดถงประชากรเสรจปป กโยงเขาเรอง DNA โยงเขา
เรองการ translation กกลายเปนวาเดกงง อาวไมใชสองเรองหรอเดก
กจะไปนงเออในหองสอบ part นนขอนนกจะหายไป ประมาณน Interviewer: ชวยอธบายเพมเตม Kanisha: กคอเหมอนกบอาจจะมแบบฝกหดบางขอและขอสอบบางขอเขากจะเรม
วา ม genotype อยางนๆ หรออะไรอยางนใชไหมคะ และถามวาถา genotype เปนอยางนแลวกาหนดลกษณะไหน มโปรตนเทานๆ ใน genotype แบบน ถามวาจะตองมรหสชด เปนแบบไหนบาง เทานน
เดกกจะ เอย อะไรอยางไร งง เชอมอะไรไมได ขอสอบขอนนก
กลายเปนวาเนาไป
Teachers’ beliefs about teaching classical and molecular genetics. The analysis also
revealed teachers’ meta-knowledge about classical and molecular genetics. The way teachers
think about the nature of classical and molecular genetics could influence how teachers teach
each unit. Some teachers viewed that molecular genetics is an extension of classical genetics and
it answers questions that classical genetics cannot explain. In addition, teachers noticed that
classical and molecular genetics associate with different biological levels. The teachers
commented that knowledge in classical genetics is static but knowledge in molecular genetics is
dynamic and continuously developed. For example, Pakorn mentioned that it is importance to
point out to students that knowledge learning in classical genetics unit could not apply to all
genetic traits.
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Interviewer: How do you introduce the first unit? Pakorn: Genetic inheritance. I will tell students that how is Mendel. Let students have critical thinking. Did he lie? Why did he have to do like that? Are there other methods? Traits that Mendel studied are called complete dominance. Is it possible in the nature? Let students think. Understand. I do not mind that the answer is right or wrong. Just ask students to think why there are no linked genes in selected genes. Students think, gather data, and analysis data. I tell students that Mendel did not see the gene. He had to imagine that there is this thing. Accidentally, someone proved that it is correct to what he thought. Scientists proved his laws that they are true. I pointed out what cannot be explained by Mendel’s laws, what reasons are. Why these are not like Mendels’ law. Such as linked gene, mutation, something.
Interviewer: Pakorn: การถายทอดลกษณะทางพนธกรรม จรงๆ จะเลาใหนกเรยนฟงวาเมน
เดล เปนอยางไร ใหเดกคดวเคราะห เอะ เมนเดลโกหกรเปลา ทาไม
เคาตองทาแบบน มนไมมวธเลยเหรอ ลกษณะทเมนเดลเรยกมนเปน complete dominance แลวในธรรมชาตเนย มนเปนไปไดร
เปลา เพอใหเดกไดคด เขาใจ คาตอบจรงหรอไมจรง ไมรแตให
นกเรยนไดคดวาทาไมไมม linked gene เลย ยนทเลอกมา ให
นกเรยนไดคดเกยวกบการเกบขอมลการวเคราะหขอมล กพยายามบอกใหนกเรยนฟงวาเนยตอนทเมนเดลเคาศกษาเนย จรงๆ แลวเคาไมเหนอะไร แลวเคากตองจนตนาการ คดวามตวนอย มตวน
อย แตบงเอญสงทเมนเดลบอกมคนพสจนวามนตรงกบทเมนเดลคด กฎของเมนเดลเนย เมนเดลใหกฎมากมการคดวาดเอนเอนาจะเปน
แบบน ยนนาจะเปนแบบน กมคนมาพสจนมนกตรงจรงๆ แลวก
พยายามชใหเหนวาตวไหนทไมตรงกบกฎเมนเดล ตวทมนไมตรงกบ
กฎของเมนเดลมนตองมเหตมผลวา ทมนไมตรงเพราะวาอะไรเชนมน
อาจจะเปน linked gene มนอาจจะเปน mutation หรอเกด
อะไรกแลวแต ประมาณนน
The emerging theme among many teachers was that classical and molecular genetics
require different types of reasoning and skills; they stated that leaning classical genetics involves
calculating and learning molecular genetics involves memorization. The teachers said that
teaching classical and molecular genetics associated different kinds of teaching pedagogies and
learning activities. For example, they expected that students spend more time doing exercise on
genetic probability in classical genetics unit, and that students spend more time on memorizing
biological terms in molecular genetics.
Interviewer: You said that you have less confidence in teaching some parts of molecular genetics, comparing to teaching genetic inheritance. How? Knaisha: It is not like that. Actually, Mendelian genetics is more about calculation and calculation is like we give students principles. Interviewer: It is non-changed law.
Interviewer: อาจารยบอกวาอาจารยเหมอนกบเขาใจในเนอหาสวนของอนพนธ
ศาสตรหรอวามความมนใจนอยกวาในเรองของการถายทอดลกษณะทาง
พนธกรรม เปนอยางไรคะ Kanisha: มนกไมเชงอาคะ คอวาจรงๆ แลวอยางในเรองของพนธศาสตรแนวเมน
เดลมนจะออกการคานวณซะเยอะ และการคานวณมนเหมอนเรายนหลก
ใหเดก
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Kanisha: Yes, giving students ideas about calculation and they will apply. But in term of molecular. I sometimes also forgot what the name of this enzyme. I know only its’ functions. Or, enzyme with this name, what are functions. Therefore, I am confident toward Mendel more. So, I think students are not different from us. Because they are many enzymes. Yes, there is also additional topic about PCR. New synthesized enzyme for PCR. Students said why there are so many. Moreover, there is also about mutation that this enzyme changes this. This enzyme changes that. There are so many. I also think students will be bored. In the chapter two, not capable students are those who are good at mathematics. However, they do not remember well. When they meet a lot of terminology, step of processes. Sometimes, like names of enzymes we cannot find roots of terminology.
Interviewer: เปนกฎตายตวแลว Kanisha: ใช ยนหลกคานวณใหเดก เดกเขาจะไป apply ไดเยอะ แตในลกษณะ
ของโมเลกล ขนาดตวเองบางทยงลมเลยวาเอนไซมตวนมนชออะไรหวา
รแตวาหนาทมนทาอะไร หรอบางตวเอนไซมชอนมนทาหนาทอะไร ขนาดตวเองยงลม กเลยรสกวาความมนใจมนจะเอนไปทางเมนเดลมากก
วากเลยรสกวาเดกกคงจะไมตางจากเรา เพราะวาชอเอนไซมมนเยอะมาก ใช ไหนจะมขางนอกทเปน PCR สงเคราะหเอนไซมใหมขนมา ทจะ
ไปชวย PCR เดกกจะแบบวาทาไมเยอะจงเลย และยงจะมเรองนวเตชน
ทเอนไซมตวนแกตวน เอนไซมตวนแกนน เอนไซมตวนใชเลาะตวนนะ กจะเยอะมาก เรายงคดวาเวลาเรยนกลวเดกจะเบอ บททสองจะไมคอยไดคอจะเปนเดกทเกงในเรองของคณตศาสตร แตใน
เรองของทองจาเขาจะไมได พอเขาไปเจออยางทบอก ศพทเยอะๆ ขนตอนกระบวนการ ซงบางทกคอถาอยางชอเอนไซมมนไมสามารถท
จะดงรากตอมาไดบางอน
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CHAPTER 5
Finding Pedagogical Tools to Improve Teaching Multiple Models of the Gene
Introduction to the Chapter
Adopting a design-based research approach, this study aims to engineer a particular
combination of learning experiences while systematically advancing the development of specific
learning theories (Cobb et al., 2003). In this case, the focus is on using a strategy of multiple
representations to create an integrated understanding of multiple models of the gene. Cobb et al
(2003) stated that design-based research is an approach in which “What works is underpinned by
a concern for how, when, and why it works, and by a detailed specification of what, exactly, it is”
(p. 13). This chapter presents the results of the development and implementation of the designed
learning materials in order to answer the remaining research questions:
• What are effective pedagogical strategies for teaching multiple models of the gene
with the goal of coherent, integrated, and meaningful understanding?
• How do the learning materials created in this design-based research project
impact student understanding of multiple models of the gene?
• What are the factors that influence the implementation of the designed learning
material in Thai classrooms?
As a prelude, in this chapter I briefly review the development of the designed learning
materials for teaching multiple models of the gene with the goal of coherent, integrated, and
meaningful understanding. This first section focuses on the essential principles underlying the
design of learning materials from projected design and emerging data. This exploration will help
advance learning theories for teaching multiple models. The next section presents five cases of
how the teacher participants implemented and adapted the designed learning materials to teach
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genetics in Thai classrooms. To explore practice in Thai classrooms, this section also includes an
analysis of teachers’ opinions on benefits and educational constraints toward the implementation.
Lastly, this chapter presents the results of the effect of the designed learning materials on
students’ learning of genetics in order to evaluate the designed tools. The results revealed that a
significant number of students in the classrooms using the designed learning materials
demonstrated integration between the classical and molecular models.
• Part I: Developing pedagogical tools to improve teaching the gene concept
• Part II: Implementation of the designed learning materials in Thai classrooms
• Part III: The impact of the designed learning materials on students’ understanding of
multiple models of the gene
Part I: Developing Pedagogical Tools to Improve Teaching the Gene Concept
This section describes the development of the designed learning materials and the
principles underpinning the materials. The learning materials were developed to solve the
problem found in the classroom that most high school students did not develop a complete
understanding of genetics after completing genetics courses. The literature review and the
textbook analysis (in chapter 2) demonstrated that the classical and the molecular models of the
gene in current curricula (and possibly in instruction) are presented discretely within particular
genetics domains. However, students need both models to explain real genetics phenomena
meaningfully, and they must be able to retrieve their knowledge appropriately to solve problems
that connect these isolated ideas. Therefore, a design challenge that this study seeks to answer is
how to help students construct explicit connections between the two models. The ultimate goal is
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for learners to acquire their own strategies for interconnecting multiple models and applying
models appropriately to solve problems.
The framework underpinning the designed learning material was based on an iterative
process of analysis including three phases of data collection: Pilot study, Development, and
Implementation phases. In the beginning, I developed the learning materials based on
conjectured strategies derived from the literature on scientific models and multiple
representations. In order to construct a conceptual understanding with integration across multiple
models of genes, students are expected to develop an understanding of genetics through
interpreting, constructing, and linking multiple representations from the classical and molecular
gene models. However, in the initial prototype, the design outcome of making explicit
connections was defined vaguely. To improve the materials, the teachers participated in
workshops and completed interviews in which they reviewed the tools. Teachers’ pedagogical
content knowledge was the preliminary resource for modifying the tools before the
implementation. Then, the analyses of teachers’ knowledge, classroom observation, and
students’ understanding helped advance principles for future implementation; these results
indicate how model integration is manifested, and most importantly, what design strategy works.
The Principles underpinning the Designed Learning Materials
The study identifies three important principles for designing learning materials: engaging
with multiple linked representations, applying multiple models in contexts, and connecting ideas
about genes, proteins, and phenotypes around a circle of representations. Firstly, a critical
principle underpinning the designed leaning materials is constructing explicit connections
between the classical and molecular models through multiple linked representations. The
rationale behind the principle is that visually linking multiple representations of the gene could
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enable students to connect their ideas of the classical and molecular models efficiently. The next
principle seeks to promote students’ competence to apply a model specific to a particular
genetics problem. The last principle supports student in integrating of both models of the gene
with proteins and phenotypes in order to build a complete understanding of how a gene controls
a phenotype (the intermediate pathway via proteins is often obscured in high school curriculum).
These three principles fit together pedagogically to create a learning environment that promotes
meaningful understanding of genetic phenomena across classical and molecular domains.
1. Reliance on multiple linked representations. The main design principle is using
multiple linked representations to integrate conceptual understanding across models. The
learning tasks center on students being challenged to generate, interpret, refine, and apply
multiple linked representations of the gene. This principle acts to help the learner organize
mental models based on the linked external representations (Kozma, 2003; Treagust & Tsui,
2013; van der Meij & de Jong, 2006). The reason for emphasis on linking multiple
representations of the gene is that the ability to translate between representations is key to
integrating conceptions of the two models and selecting an appropriate model to solve problems.
Representations are essential for communicating ideas in the classroom and in the
scientific community. Tytler, Prain, Hubber, & Waldrip (2013) showed that representations can
function in many ways. For example, they can be used as (a) perceptually-based resources for
imaging, visualizing, testing, and reasoning; (b) products of internal mental models or artifacts of
thoughts; and (c) evidence-based causal accounts of phenomena. diSessa (2004) and Vosniadou
(2008) deliberated the role of representations in eliciting and enhancing conceptual knowledge in
learning science. Often multiple representations are used to explain a concept because specific
information can be conveyed in a specific representation (de Jong et al., 1997). The affordance
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functions of multiple representations are like tools for conceptualizing and coordinating different
dimensions, purposes, and contexts (Treagust & Tsui, 2013).
To design the learning materials, I drew upon literature on multiple representations in
science education; however, the design solution that served as the focus for my research differs
from the literature. Prain & Waldrip (2013) posited that “Multiple representations’ refers to the
capacity of science discourse to present the same concepts and processes in different modes,
including verbal, graphic, and numeric forms” (p. 15). Ainsworth (1999) proposed that multiple
representations help enhance learning science by supporting complementary cognitive processes,
constraining misinterpretation, and instilling deeper understanding of a phenomenon. Many
studies investigate learning and teaching with multiple representations across different modes in
science topics (Ainsworth, 2006; de Jong et al., 1997; Gilbert, Reiner, & Nakhleh, 2008; Kozma,
2003; C.-Y. Tsui & Treagust, 2003; Tytler et al., 2013). My study attempts to build connections
between different scientific models across genetic domains (instead of focusing on different
modes of representations within the same concept). Therefore, the links are between multiple
representations from the classical and molecular models, regardless of mode. Each gene model
entails different modes of representations; for example, the classical representational model is
explained with symbolic representations of alleles, visual representation of chromosomes, and
textual description.
The literature offered potential design heuristics for integrating the gene models with
multiple linked representations. Kozma (2003) suggested that multiple representations need to be
linked to make the explicit connections between entities, processes, and phenomena. Kozma
(2003) states that multiple representations should have “concurrent displays” and that “linkages”
would allow students to map features of multiple models. Furthermore, these strategies allow
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building perceptual connections among representations and coordinating different dimensions,
purposes, and contexts between different models. Different gene models are constructed using
different terminology, concepts (e.g. particle and sequence), and functions (e.g. inheritance and
expression). To integrate knowledge from both models for meaningful explanation of genetic
phenomena, the models must be combined.
In learning about genes, students are challenged by the transition between multiple
models in different domains. For secondary students, the conceptual demands of switching
between different models can be overwhelming. By having students illustrate visually the
connections between representations for the two models, the cognitive effort required to mentally
integrate disparate sources of information can be reduced or eliminated. Thus, students can
construct explicit connections between the models. In the designed learning materials,
representations related to the classical model and those related to the molecular model are
concurrently displayed to create referential links between them, and students are encouraged to
coordinate, implicitly or explicitly, both models to explain genetics phenomena (see example
from activity 3 in the Appendix B).
2. Applying multiple models in contexts. In addition to comprehending the meaning of
models as tools for explaining genetic phenomena, students should be able to move flexibly
between different models and apply appropriate models to solve the problems. By engaging in
authentic problems with the explicit use of models, students will develop understanding of the
topic by connecting models to phenomena (Harrison & Treagust, 1998). Based on the literature
on experts and novices, expertise is viewed as being able to understand the domain knowledge
from multiple perspectives (NRC, 2005). Therefore, expertise is seen as the ability to readily
switch between representations (de Jong & Ferguson-Hessler, 1991), and when performing a
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problem or solving task, to select the representation that is most suited for that problem or task
(Tytler et al., 2013). This type of understanding requires students to have both conceptual
knowledge (knowing what) and strategic knowledge (knowing when, where, and how our
knowledge applies) in learning science.
One of the learning goals is to master a strategic knowledge in regards to the selection of
the most appropriate model for use in problem solving. Applying multiple models in a genetic
context is a key principle in bridging multiple gene models and understanding the explanatory
function of the models. In regular tasks in the classroom, students are commonly asked (a) to use
the classical model to solve problems concerning genetic inheritance and (b) to use the molecular
model to solve problems concerning gene expression. In the designed learning materials,
students gain experience in coordinating both models to solve problems. Students are asked to
use both gene models in solving genetic problems by using (a) either the classical model or the
molecular model and (b) both the classical model and the molecular model concurrently.
I will focus on the second type of questions in the analysis, because using the two models
concurrently is particularly important for integrating multiple models. The essential feature of
this type of question is engaging students in particular situations (genetic phenomena). The
designed situation needs to be an amalgam of both models to allow students to understand the
particular explanatory functions of both models; this type of question is not common in the
current curricula. Switching/crossing from one model to another is a central part of the demands
of the situation.
3. Constructing a background on the structure and function of proteins. To develop
a coherent understanding of the entities and processes that constitute genetics phenomena, in the
designed learning materials, students are encouraged to solve genetics problems by addressing
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genetic material, proteins, and phenotypes in integration. The literature shows that high school
students lack an understanding of the structure and function of proteins in relation to genetic
traits (Duncan, 2007). The materials support students in constructing explicit connections among
the classical gene, the molecular gene, and proteins. In addition, activity 4 (building a protein)
allows students to build a three-dimensional representation of proteins and to change the protein
structure based on altered sequences of instruction.
The Designed Learning Materials
The designed tools are composed of a range of learning activities that aim to assist
students in developing their understanding of multiple models of the gene. This sequence of
representational challenges will elicit students’ ideas, enable them to explore and explain their
ideas, extend their ideas to a range of new situations, and allow opportunities to integrate their
representations meaningfully. Greeno & Hall (1996) claim that students benefit from multiple
opportunities to explore, engage, elaborate, and re-present understanding in the same and
different representations. Teachers could use the materials as lesson plans, learning activities,
and formal assessments. The selected learning activities reviewed here are the activities that the
teachers chose to implement in the classroom (see Appendix B). The learning activity on
thalassemia, which requires a longer period, was not implemented due to time constraints.
Activity 1: Representations of genetic material. In this activity, students have
opportunities to demonstrate their understanding of each gene model and what it signifies.
Students are encouraged to explain and generate their links between multiple representations of
both models. Students then combine their ideas of both models to provide a definition of the
gene. Students are challenged to explore the idea that homologous chromosomes are not
identical: they just code for the same genes, but do not necessarily have the same alleles or the
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same sequences. Students can compare and reconcile their representations with those of their
peers or teachers.
Figure 13. The representations in Activity 1 that students are asked to connect.
Activity 2: Explaining scenarios about genetics. In this group activity, students are
asked to use multiple representations to explain five scenarios related to genetics. Each scenario
requires a range of multiple representations of the classical and the molecular models. Some
scenarios can be explained with both the classical and the molecular models.
Figure 14. Examples of representations and a scenario in Activity 2
Activity 3: Gene expression of pea plants. This activity is situated in an exploration of
gene expression of flower colors in pea plants. The situation is designed to anchor multiple
representations from both models. This activity allows students to use perceptual clues to make
Scenario 4: A scientist extracts DNA from the clam and found that a nucleotide sequence of that clam is AAAGGCTTCTCC. What is a type of protein that a clam will produce? What could be the genotype and the phenotype of this clam?
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connections between multiple representations of the classical and molecular models. The
relationship among genes, proteins, and phenotype is presented explicitly through the biological
processes.
Figure 15. Examples of representations shown in Activity 3
Activity 4: Building your own protein. This activity supports students in deepening
their understanding of the structure and function of proteins and applying both gene models to
solve a genetic problem. In each group, students build a protein structure based on a nucleotide
sequence of each allele. This allows students to visualize the effect of changes in a nucleotide
sequence on the structure and function of a protein and to visual different structures of proteins
constructed from different alleles. The students then discuss the relationship between genes and
proteins, leading to different phenotypes. This activity is adapted from an activity developed by
the Center for BioMolecular Modeling (http://www.3dmoleculardesigns.com/ 15_Tacks.pdf).
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Figure 16. Examples of proteins’ structures created by the students in Montana’s classroom to
represent proteins from different alleles in Activity 4
Redesigning the Designed Learning Materials
The learning materials were continuously redesigned through iterations of data collection
based on teachers’ comments from the workshops and the results from the implementation. The
design guidelines needed to be continuously refined and tested. Examples of major modification
of the design framework based on the results include the following:
Data analysis on knowledge structure of teachers and students clarified what mastery of
making explicit connections across multiple models would look like and what would count as
integrated knowledge. This helped define the essential features in the design for shifting from
partial connection to integration. Mapping external representations helped students build visual
connections from alleles in the classical model to DNA sequences in the molecular model. For
supporting understanding at the integration level, learning activities should anchor both models
in solving problems about authentic phenomena.
The focus on the application of multiple models originally emphasized the selection of
the appropriate model to solve genetic problems in a particular genetic domain: the knowledge
was conditioned on a set of circumstances. Based on the analysis, the focus shifted to a design
Red color Gray color
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principle supporting the coordination of both models concurrently as a means of coping with the
complexity of genetic phenomena.
The analysis also revealed that the situations (genetic contexts) are important for building
integrated multiple models. Connections based on decontextualized activities were limited to
partial connections between the structural features of the two models, and did not extend to their
functional features.
Based on the teachers’ comments, the learning activities were altered to include the
biological pathways of gene expression for both recessive and dominant alleles in order to
illustrate the underlying processes that connect genes and proteins.
Part II: Implementation of the Designed Learning Materials in Thai Classroom
One prominent characteristic of design-based research is that it is grounded in both
theoretical and practical contexts. This section presents a descriptive discussion on the practical
context that helps illustrate how, when, and why the tools work. This analysis of the
implementation should inform the customization of the designed learning materials for future
implementation.
Classroom Implementation
The approach and findings reported in this chapter focuses on the pedagogical tools for
teaching the gene concept and are situated in five high schools in Thailand. I worked with
teacher participants to develop the tools. The five teachers then implemented the tools in their
genetics classrooms. Although the materials specified instructional moves in detail, I sought a
significant amount of teacher input for implementation and modification of materials. Doing so
made the approach feasible by fostering researcher-teacher collaboration and the development of
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teachers’ practice—necessary for modifying the tools and eliciting students’ engagement.
Classroom observation showed that the teacher participants incorporated the tools differently in
terms of teaching approaches, sequences of the activities, and time spent on the activities.
Common genetics teaching in Thai classrooms. Before, turning to the implementation
of the tools, I will describe instructional approach and curriculum sequence of common genetics
teaching in Thai high school classrooms. The teachers planned their lesson according to the
guidelines provided in the national science curriculum launched by the IPST (OBEC, 2008). The
instructional sequence mainly followed the structure of contents presented in the biology
textbook (IPST, 2005). The first unit begins with classical genetics, focusing on genetic traits,
Mendel’s laws, monohybrid cross, dihybrid cross, and chromosome segregation. The second unit
covers molecular genetics, focusing on DNA structure, mutation, DNA replication, and protein
synthesis. The main teaching approach was traditional and teacher-centered meaning, in that
instruction was based on lectures, textbooks, and individual assignments. Thus, pedagogical
approaches for promoting conceptual understanding such as inquiry, questioning, or group
activity were rarely shown. The content was presented as masses of factual information without
necessarily facilitating the acquisition of an understanding of the main concepts or providing
connection between topics. The reason why teachers favored a more traditional approach could
be because the large classroom size, with about 45 students per classroom, and the maintenance
of objective educational standards.
Building on this teaching tradition, the teachers were encouraged to integrate the learning
activities in their classrooms. All teachers incorporated the learning materials into the molecular
genetics unit, after they taught classical genetics.
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Integrated lesson. Both Kanisha and Patcha mapped the activities into their lesson plans
according to related topics. For example, they introduced activity 1 to teach about genetic
material, and then used activity 4 after the protein synthesis lesson. This approach supported
students in promptly constructing an integrated knowledge about the gene when they learned
other genetics concepts in the classrooms. In this way, students could effectively connect
multiple concepts and have more opportunities to explore and manipulate multiple linked
representations. Based on the classroom observations, students’ responses in these classes
showed that most students effectively made connections between the models in solving
problems.
As an example, I will discuss Kanisha teaching practice, which was consistent with
Patcha’s approach. Kanisha began the molecular genetics unit with the discovery of genetic
materials. To elicit students’ ideas, Kanisha reviewed the definition of the gene by asking
students to describe the gene and draw representations. Then, the students used activity 1
(Representations of genetic material) to make links between multiple representations of the gene.
Multiple linked representations then were discussed and evaluated within a whole class
discussion. Although activity 1 does not indicate which phenotype a gene in the pictures
controls, Kanisha added a prompt that the gene in both pictures controls a shape of seed trait. In
the next class, students learned about gene expression and engaged in activity 3 to explore the
function of a gene to control amino acid sequence, in both the classical and the molecular models
together. This approach helped students gradually develop integration between the classical and
molecular models before applying their ideas to solve genetics problems.
Interestingly, Kanisha changed the sequence on mutation, which normally is taught
before gene expression, to be after protein synthesis. This instructional modification could
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effectively help students picture the relationship between genes, proteins, and phenotypes more
vividly. She first presented activity 4 (Building your own protein) after students learned about
transcription and translation processes from instructional media with 3D-animation. Students
therefore had the opportunity to visualize the molecular processes presented in the media before
building the protein model corresponding to assigned alleles or sequences. Since activity 4
involved unfamiliar concepts and hands-on activity, Kanisha first had difficulty assisting every
group of students in the large classroom. Therefore, she decided to use activity 4 again when she
taught students about different types of mutation, such as silent, nonsense, and frameshift
mutations. Students learned how mutation in a DNA sequence leads to a malfunctioning protein
in homozygous recessive genes by manipulating gene and protein sequences and presenting their
group protein representations to the class.
The excerpt below shows her decisions in integrating the designed learning materials in
her classroom and the reason why she did not implement activity 2.
Interviewer: About activity, will you use it again next time? Kanisha: I think I will use it again. Interviewer: Will they be two activities that you used in the class? Kanisha: Yep, I think they have benefits to students a lot. I also think the activity that DNA dissolves in the water is good. However, we do not have materials for this, and no tools. I did not use it. Just explained them what it is. Next, purple and white flowers and protein, I think I will use it again. These show pictures and they go to the same direction. When using these activities, there is a flow. They connected everything that already learned from beginning to here. It finalizes everything together. Interviewer: How about the first one? Kanisha: Actually, the first one is good. The one with
Interviewer: แลวถาพดถงตวกจกรรม คอคาถามเกยวกบการใชของอาจารย อาจารย
คดวาอาจารยจะนามาใชอกไหม Kanisha: คดวาจะนามาใชอาคะ Interviewer: จะเปนในสองสวนกจกรรมทอาจารยเลอกมาใชใชไหม Kanisha: คะ มนคอนขางทจะเปนประโยชนกบเดกคอนขางมาก จรงๆ มนจะมตว
นคอตวท DNA ทเอามาละลายนา แตวาตวนเราไมมวตถดบไมม
อปกรณอะไรดวย กเลยไมไดใชแตอธบายใหฟงเฉยๆ วาคออะไร ตอไป
ไปกจกรรมดอกมวงดอกขาวกบตวโปรตนกจะเอามาใชอก และกเหน
ภาพอะไรอยางนดวย และมนคอนขางทจะไปในทศทางเดยวกน คอ เหมอนกบทากจกรรมสองตวนและมนเหมอนเชอมโยงทกสงอยางท
เรยนไปแลวตงแตตนมากองอยตรงนเพอเปนเหมอนตวขมวดปมสดทาย Interviewer: แลวกจกรรมแรกละคะ Kanisha: คดวาจรงๆ ตวแรกกดคะ แตวาตวทเปนเรองของใหดโครโมโซมกบ
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chromosome and genes is also good. This helped students monitor their own leaning if they understand relationship between genes and chromosome. Students have better understanding. Genes are part of chromosomes, but they are coiled to small particle. Interviewer: Why don’t you use this activity? Kanisha: The one with picture (activity 2), questions were like, hmm. They were like for assessment. When students learned everything already, they can use this one. I do not think using it as learning activities is a good idea. However, using it for checking conceptions at the end is okay. Interviewer: Why did you use two activities, purple flower and protein models? Kanisha: For purple flower, it helps students’ imagination. This links from molecule to Mendalian genetics. It is very clear for Mendelian genetics. This helps students understand this topic better. Students question what a dominant gene is actually and what a recessive gene is. For protein topic, it helps students understand when protein’s structure is changed, this makes change in traits. I thought these two topics were connected very well.
gene อนนกดเหมอนกนกใชตวนดวย เพราะวาตวนมนทาใหเดกเขาได
เชคความเขาใจของเขาเองวาคอ ตกลงรหรอเปลาวาโครโมโซมกบ gene สาพนธกนอยางไรอยสวนไหน กทาใหเดกเขาใจไดมากขนวา gene คอสวนหนงในโครโมโซม แคมนขมวดๆ เขาไปเปนกอนเลกๆ Interviewer: และทาไมถงเลอกทจะไมใชอนน ตวกจกรรมคาถามทเปนรปภาพ Kanisha: ตวทเปนรปภาพเยอะๆ ตวคาถามคอนขางจะ มนเปนอะไรทเหมอน
ขอสอบมากกวา มนเหมาะกบการทจะใหเดกไป สมมตวาเรยนจบ
ทงหมดทงมวลแลวกนาใหเขาทาในตอนสดทายมากกวา ไมคดวาใส
ในชวงกจกรรมการเรยนรจะด แตวาคดวาเอาไปเชคconception ใน
ตอนทายนาจะได Interviewer: แลวทาไมอาจารยเลอกทจะใชสองเรองคอ ดอกมวง กบตวโปรตน Kanisha: ตวดอกมวง ทาใหเดกเหนภาพไดคอนขางชด กบการเชอมโยงจาก
โมเลกลสเมนเนเรยลเจนเนตกส เมนเนเรยลเจนเนตกสตวนนคอนขางท
จะชดมากๆ ทาใหเดกคอนขางทจะเขาใจในเรองนมากขนประมาณนน คอเขากคงจะมสงสยวา gene เดนคออะไร gene ดอยคออะไรตงแต
แรก สวนเรองโปรตนมนทาใหเขาไดเขาใจวา การทกอนโปรตนมน
เปลยนสภาพหนาตาไป ทาใหลกษณะทออกมาเปลยนไปเลยเชนกน เลย
คดวาสองเรองนเชอมโยงกนไดด
Interviewer: Why do you use activity 4 to teach mutation? Kanisha: When I saw the activity about translation, I can see that this activity, hmm, the first activity is to help see that recessive gene is from mutation. From the codon for a protein, it is changed to stop codon. This helps me think that if I used this activity in teaching mutation like point mutation, it should work. Students can see a clear picture. If we only lecture that silent mutation, nonsense mutation, students would not see pictures. If students use protein models, coiling toobers, students will see pictures. Also, if we didn’t do it at the same time, students would not remember the previous coiled structure. That’s why I asked them to do comparison between groups. From normal DNA to each type of mutation. And, asked them to compare. Comparing to friend’s models. Students can build their own knowledge. They will remember. From what they normally used to just writing amino acid sequences in the paper, there was another step helping them seeing structure.
Interviewer: ทาไมอาจารยถงใชกจกรรมสสอนเรองมวเทชนคะ
Kanisha: กคอตอนทเหนกจกรรมเรอง translation กเหนเลยวากจกรรมเรองน
ในใบกจกรรมชดแรกทใหกคอเราจะเหนวา gene ดอยมนเกดจดหนงท
มวเทชนขนไป และกลายเปนวาจากโคดรอนทสามารถโคดใหโปรตน
กลายเปนซอฟตโคดรอนไปเลย มนเลยทาใหเราคดวาถาเกดตรงนเราเอา
มาใสในกจกรรมการมวเทชนเปนพวกพอยทมวเทชนกดนะ เพราะวาเดก
จะเหนภาพชด คอเราพดอยางเดยววาไซเลนมวเทชน นอนเซนท มกซ
เซนทอะไรอยางนเดกมองไมเหนภาพ แตถาเกดไดลองเอาโครงสราง
โปรตนมาลองขดๆ ดเดกกจะไดเหนภาพ และถาเกดเราใหเขาทาไป
พรอมๆ กนทงหมด เขาจะจาภาพขดกอนหนานไมไดวาขดหนาตาเปน
อยางไร กเลยจดการเปรยบเทยบ และใหโปรตนขนมา ใหโคดอนขนมา
และใหเขาไปแปรงกนเอง DNA ตงแตปกตมาจนถงไป และกใหเขา
มายนเปรยบเทยบกน ใหเพอนมาดเปรยบเทยบ ตอนนนเดกๆ จะไดคอน
เซปดวยตวเองแลว เหมอนกบเขาจะจาไดดวย และเขาจากทวาเมอกอน
เขยนแคอามโนแอซส แตกไดเหมอนเพมเตมขนมาวามนมโครงสราง
เปนอยางนน
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Supplementary activities. Montana and Salee treated the designed materials as extra
activities to enhance students’ understanding of genetics, not to serve the primary learning
objectives of the lesson. These teachers implemented the learning materials with a different
approach, using all activities together in one period after the molecular genetics unit. With this
approach, as with the previous approach, the teacher played an important role in facilitating
students’ learning. Both teachers guided students to explore multiple linked representations
successfully. The difference was that students might not be aware of how the activities
correspond to the content they had learned from the lecture. In addition, the students, who
struggled from the first activity, were not ready to learn the next activity.
Due to dissimilarities in their classroom spatial structures, Montana, who taught in a
science laboratory classroom with group seating, arranged more group activities, while Salee
who taught in a small lecture classroom with individual seating, used the tools for individual
assignments and activities in pairs. Salee also mostly assisted only students in the front rows of
the classroom. In comparison with other teacher participants, Montana provided more
opportunities for her students to share their ideas and lead the classroom. The students presented
their work to the class, and Montana respond to students correspondingly. In addition, she
extended the instructional time so students could engage in all activities.
Homework assignment. Wanida employed the designed learning materials as an
assessment tool to evaluate students’ understanding of genetics. Using the materials for
assessment could provide valuable information about students’ learning; however, this choice
also meant that these teachers could not facilitate students while working to build connections
and that the students did not have enough time to engage in the activities. Ideally, the tools were
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designed to engage students in order to conceptually integrate their factual knowledge of
genetics.
Wanida introduced the connection between the classical and molecular models using the
pictures from activity 1, when she taught about double helix structure and the location of genetic
material in chromosomes. Then, she followed her lesson plan by lecturing on topics listed in the
molecular genetics unit, and after lecturing on gene expression, she assigned these designed
activities in this study as individual assignments. She collected students’ works and evaluated
their responses. The students shared and discussed their written responses in the next class, and
Wanida guided the students to correct responses. Wantida explained that she did not implement
the tools as learning activities because she did not have enough time to cover necessary content
standards in the molecular genetics unit. Based on the observation, she spent more time teaching
the classical genetics unit than the typical hours depicted in the national curriculum; in particular,
students practiced genetics problems predicting genotypes and phenotypes and discussed non-
Mendelian traits.
Teachers’ Opinions on Implementing the Learning Materials in Thai Classrooms
The teachers shared perceptions of benefits, challenges, and constraints in implementing
the designed learning materials in their classrooms. The analysis of teachers’ opinions post-
implementation indicated that the teachers perceived significant gains in student learning from
implementing the designed learning materials and that challenges in practice were due to time
limitation, student motivation, and conflicting learning objectives. Moreover, an emerging theme
regarding the effect of pressure from university admissions committees on student motivation,
curriculum planning, and teaching practice was discussed; this issue was raised by most Thai
teacher participants during the interviews and the workshops.
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The benefits of the implementation. All teacher participants anticipated that the
designed learning materials would significantly help increase student conceptual understanding
of genetics. With these potential benefits, all teachers commented that the learning materials
could be applied to other Thai high schools if more explicit teaching direction is given and that
they would integrate the tools in their future classes. The benefits of the designed learning
materials toward student learning, based on the teachers’ comments include the following points.
First, students developed a deeper understanding of main ideas, particularly on genes and
proteins (see the excerpt of Kanisha below). Students were able to connect genetics concepts
they had learned in the classroom. Moreover, students could apply their knowledge about genes
and proteins in everyday life situations (see the excerpt of Montana below). Students’ motivation
in learning genetics was potentially increased because of active learning in the activities.
This approach also revealed students’ needs and differences in understanding, and the
teachers could address them in their teaching. For example, Patcha stated that the activities help
uncover that students did not fully understand the meaning of genetic information. Salee added
that through using the designed activities she could observe students’ ideas about DNA structure
and protein synthesis processes.
Interviewer: Can you share your experience in using the activities? Kanisha: Now, I teach two classrooms. One room is in the research. Another one is with another method but similar, except developed innovation. I think in the classroom in research group students know application and understand key concept better, especially about central dogma. They understand key concepts better comparing to another room without the innovation. Interviewer: Can you explain what key concepts that you mentioned? Kanisha:
Interviewer: อาจารยคดวาทลองใชไปเปนอยางไรบาง
Kanisha: คอจรงๆตอนนกคอสอนสองหองควบกน คอหองหนงจะอยในวจย อก
หองหนงไมไดอยในวจย เรากจะสอนคนละแบบกนแตวาใกลๆ เคยงกน
ยกเวนเรองทวาเอานวตกรรมของอาจารยมาใส รสกวาหองททาวจยอย
เขาจะเขาถงการประยกตใช เขาถง key concept ไดดกวา โดยเฉพาะในเรองเซนทรลดอกมาร คอนขางทจะทาใหเขาเขาใจ key concept ไดดกวาเมอเทยบกบหองอกหองหนงทเขาไมไดใช Interviewer: อยากใหอาจารยอธบายเพมเตมวา key concept เรองอะไร
Kanisha: คอกวาเขาจะเขาใจ key concept คอ เลนเอาถงขนทากจกรรมทา
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For them to understand key concept. Even I used activities and building models, students partially understand but not all. When they make models, it shows that some students do not understand or do it very wrong sometimes. Sometimes, they still confused translation, transcription and DNA. They are all mix up. I think having innovation is better.
โมเดลทาอะไรแลวเขาถงจะพอเขาใจบาง แตกยงเขาใจไมหมด พอได
ลองใหเขาทาโมเดลขนมากพบเลยวาเดกบางคนยงไมเขาในบางหรอผด
มหนตเลยกม บางท translation คออะไรบางทเขายงสบสนกบ transcription กบ DNA อยเลย ใช กตกนกระจยกระจายไป
หมดประมาณนน กเลยทาใหมนวตกรรมนาจะดกวา
Interviewer: What is the benefit that you think students get from learning with the activities? Montana: They got benefit that they learned what a gene is. They learned where it is located and connect to chromosomes and DNA. Then, after DNA, studying about mutation and wrong sequence (sic.). Yes. Then, talking about connection to real situation. Situations that we meet in everyday life. One scenario in the activity is caused by changes from chemicals in industrials. It results changes in sequences of genes. This will help student learn and connect to changing environment, environment that will have a result to them.
Interviewer: อาจารยคดวานกเรยนไดประโยชนอะไรบางจากการเรยนดวยกจกรรมน
Montana : เขากไดประโยชนของ จรงๆกคอรวา Gene คออะไร เขากรแลวเขาก
รวาอยทไหนแลวกมาเชอมโยงกบโครโมโซมมาเชอมโยงกบ DNA พอ DNA มาดถงความผดปกต ลาดบความผดปกต ใช แลวกมาพดถงสอดคลองกบสถานการณจรง สถานการณทเจอใน
ชวตประจาวนทเกดการเปลยนแปลงเนองจากสารเคมในโรงงาน มผล
ตอลาดบของ Gene อนนจะชวยใหเดกเขาใจ เชอมโยงกบ
สภาพแวดลอมทจะเปลยนไป กบสงแวดลอมทจะมผลกบตวเขา
Not only did the learning materials benefit students, but the teachers reported that the
materials enriched their knowledge. All teachers commented that by participating in the research
they expanded their knowledge about the gene concept and protein structure (see the excerpts of
Kanisha and Salee below). This suggests that the workshop effectively helped teachers advance
their knowledge of the connection between the classical and molecular models.
Interviewer: How have your knowledge changed when you participated in this research? How have your teaching changed? Kanisha: About my knowledge, I have a better understanding. Like dominant gene, recessive. I understood that dominant gene, recessive gene they have totally different codon sequences. In fact, it could be minor mutation that changes it to recessive gene. My understanding is deeper. For students, I think they may have better understanding and I think if they use their knowledge in everyday it will be better. Interviewer:
Interviewer: แลวตวอาจารยเองพอไดเขามารวมทาวจยน อาจารยมความรทางพนธ
ศาสตรเปลยนแปลงไปอยางไรบางหรอวามการสอนของตวเอง
เปลยนไปอยางไร Kanisha: อยางเรองความรของตวเองกดขน สาหรบอยางในเรองของ gene เดน gene ดอยทาใหเขาใจมากขน เพราะเมอกอนอาจจะเคยคดวา gene เดน gene ดอยมนจรงๆ มนคอ gene มรหสโคดอนคนละตวกนเลย แตจรงๆ มนแคเกดมวเทชนเลกนอยกเปน gene ดอยแลว กทาให
ความรของตวเองคอนขางทจะลกขน สาหรบเดกๆ คดวาเดกๆ เขานาจะ
ไดรบความเขาใจทมากขน และคดวาถาใหเขาไปใชในชวตประจาวนคด
วาเขานาจะใชไดดขน
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What do you mean by understanding? Give example. Kanisha: The gene concept. Phenotype controlled by genes. Where is it actually from? Gene has minor mutation; it is changed to recessive gene.
Interviewer: ความเขาใจทอาจารยพดถงหมายถงอะไร ยกตวอยาง Kanisha: เรอง gene คะ เรองฟโนไทปทเกดขนจาก gene มนเกดจากอะไร
กนแน เรองการทวา gene มมวเทชนนดเดยวกกลายเปน gene ดอย Interviewer: How have your knowledge changed when you participated in this research? and your teaching? Salee: About genes. And that I do not get depth about proteins, DNA, types of proteins. Polar or non-polar is what I studied with other colleges. If it is acid. This is about connecting molecules, about gene sequences controlling proteins. It helps me having a better understanding and I can explain students. And. That’s one, protein structure. Linking in the models. That helps a lot.
Interviewer: แลวตวอาจารยเองพอไดเขามารวมทาวจยน อาจารยมความรทางพนธ
ศาสตรเปลยนแปลงไปอยางไรบางหรอวามการสอนของตวเอง
เปลยนไปอยางไร Salee: กจะเกยวกบเรองยนแลวกเรองทเกยวกบเรากไมคอยลงลกไปเรอง
โปรตนใน DNA ชนดของโปรตน มขวไมมขวอนนเปนความรทแลว
กศกษาเพมเตมกไปถามครเขา ถาเปนกรดอะไรใช อนนกคอการรวม
ของโมเลกล แลวกเกยวกบเรองลาดบของยนทไปควบคมโปรตน อะไร
นน กคอมนทาใหเรากระจางเวลาอธบายใหเดกก แลวกมเรอง อนนแหละเกยวกบโครงสรางของโปรตน ลกษณะการจบ
ตวจากทเปนโมเดลนะคะกจะชวยเราไดเยอะ
The challenges in implementation. Although the teachers found advantages of the
designed learning materials for student learning and for their own understanding of genetics, they
were aware of potential challenges hindering the implementation. The teachers reported that they
could not implement all activities mainly due to limited instructional time and extensive material
to cover.
To illustrate, all teachers reported that this approach could be initially more time-
consuming than their current practices. Patcha, Montana, Salee, and Kanisha voiced their
concerns about demands (from schools, students, and parents) to cover all content standards and
spend time practicing drills for the exam. Thus, there was not enough time to implement new
teaching strategies or learning materials. Montana, Malee, and Wanida stated that they lacked
motivation to prepare and develop confidenct to teach new learning materials. Wanida, Nampen,
Malee, Patcha, and Uma mentioned that lecturing students directly about the correct connections
between the gene models would be less time-consuming. This suggested that their beliefs and
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expectations regarding learning differed from the goal of the designed materials, which is to
promote deeper, conceptual understanding— not merely the memorization of facts for exams.
Secondly, during the intervention implementation, the teachers expressed their beliefs,
attitudes, and experience regarding their students in the genetics classroom. Patcha, Kanisha,
Montana, and Salee reported that in general many students in their classes lacked motivation to
learn genetics. The students did not pay attention in the classroom and did not read the
instructions of the learning activities carefully. Salee, Wanida, and Montana stated that some
students might not have enough background knowledge, particularly of the molecular structure
of proteins. Comments on the levels of difficulty of the activities for Thai classrooms were
divided. Salee and Montana said that some questions, especially those requiring writing, were
too difficult for their high school students. On the other hand, Kanisha and Wanida said that
some questions were too easy for students in the science track and they believed that the
activities involving learning by doing were not appropriate for the high school level.
Other challenges that teachers mentioned were related to educational contexts of each
school. The learning materials were not appropriate for the large number of students that are
typically present in a Thai high school classroom, because teachers could not spend time
assisting many small groups during the activity. The need for materials for the designed activities
could be a challenge for some schools with few resources.
The conditions of future implementation. The teachers also shared what they saw as
necessary conditions for effective use of the designed learning materials. All teachers suggested
that the materials should include more activities and more examples. In addition, the learning
activities should include authentic scenarios, real sequences of a gene, and genetic traits related
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to humans. The teachers claimed that learning with real life examples could enhance student
motivation and understanding in genetics.
Regarding teaching approach, some teachers suggested that the designed learning
materials should be integrated into the genetics lesson, rather than using as supplementary
materials. Wanida, Salee, Nampen, and Teera commented that the activities could be used for
formative or summative assessments, as well. Furthermore, Nampen and Wanida suggested that
the activities should include direct instructions and learning objectives, so that other teachers
could follow instructions on how to use the activities in their classrooms. Montana, Salee, and
Pakorn also reported that they needed additional assistance for scaffolding the activities before
teaching.
The pressure from the university admission in Thai education contexts. During pre-
interviews, classroom observations, and post-interviews, the teachers were asked what informed
their decisions in planning the genetic curriculum. One emerging theme raised by all participants
was the pressure from the university exam, which impacts genetics education in Thai classrooms
in general. All teachers stated that this preparation for university admission influenced teachers’
decisions and practices on many levels of school curricula, teaching strategies, and classroom
management. This issue also impacted teachers’ decisions in selecting activities and
implementing the designed activities in this study.
School curriculum. Nampen, Patcha, and Pakorn commented that school curricula were
tailored based on the exam. For example, Nampen said that some schools, including her school,
changed the organization of the content by teaching classical genetics in grade 10 and teaching
molecular genetics in grade 12, due to pressure that students needed to finish all content before
the exam. Genetics is taught at grade 12 in most high schools in Thailand during a time in which
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students need to prepare for university admission. In this way, classical and molecular genetics
units were taught even more discretely, which might have reinforced the classical model as the
default model in students’ minds.
Teaching pedagogy. The teachers commented that they could not integrate all designed
activities in their teaching, because they did not have enough time for the activities. The teachers
said that they should cover all content and teach extra content so that their students would get
high scores in the exam. Wanida, Patcha, and Montana also emphasized the need of practice
drills for the exam in the classroom. Some teachers also commented that some students had
learned genetics from tutoring outside the schools, so that the teachers could not engage students
in their teachings.
Classroom management. This problem concerning student engagement also impacted the
issue of classroom management as well. The teachers shared that they permitted students to work
on other subjects during their classes in order to prepare for their exams. For example, students
could do other work such as physics homework in biology class.
This pressure leads to a tension between teaching for understanding and teaching for the
exam, and to a conflict between teachers’ beliefs and their practices. To illustrate, the teachers
believed that students should develop meaningful understanding of genetics by connecting ideas
and applying their knowledge in authentic problems. The paradox is that the teachers also felt
constrained to help students pass the exam, which focuses on detailed facts. The teachers stated
that one of the teaching demands was to cover enough content by lecturing and then to help
students practice for exam questions. Consequently, in order to modify and implement the
designed learning materials in Thai genetics classrooms, the remaining questions are how to help
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teachers integrate the tools into their practice under this pressure and how to ameliorate the
tension between the conflicting purposes of learning in the current system.
To illustrate, Patcha’s explanation indicated the conflict that she had between teaching
for the exam and teaching science for everyday life. She then reported a problem regarding
student participation in the classroom. Similarly, Pakorn faced the problem of student attention.
He commented that tutoring trains students to know how to quickly answer right answers for
exams, but they do not understand the main concepts of biology. This problem of university
admission influenced teachers’ attitudes on learning, teaching, and curriculum planning.
Interviewer: What do you think about using this curriculum to other schools? Patcha: I think it is good. Good but students here do not study. If you don’t study, you should not interrupt. It is fault that makes them. We should force them but when we do not force them, they do not understand. They do not know. Patcha: They do not understand. I am not sure if this is due to my explanation process or if they do not understand or if they do not listen to me. However, I think it is more likely because they do not listen to me. In my classroom, I know that they already read the books sometimes. Sometimes they already read this topic. They asked if it is alright not to study. Really, if you ask me, I think it is okay but no speaking in class. Don’t force you to listen but you need to study. I’m kind to them. From 50 students, not all of them are like that. They do not take responsibility. They just listen and do not think, note. They could be lost easily. Interviewer: This problem is not only here. Patcha: Everywhere, it is not only here. Student background in responsibility is less. In the past, we have to learn for ourselves. When we do not understand, we have to read. But, they do not. Therefore, they could not think that. This is the failure of education. I do not blame them because everyone wants to pass the entrance exam. If they
Interviewer: อยากใหอาจารยพดถงวาถาเกดวาถานาหลกสตรนไปใชกบโรงเรยน
อนมความเหมาะสมไหม ยงไง Patcha: ทจรงแลว คดวาดนะ ดแลวกทนเนยมาพลาดตรงทเดกไมเรยน โอเค you ไมเรยน you กอยามาแสม มนกเปนการพลาดทาใหเขาเนย
คอเราควรจะบงคบเขาแตพอเราไมบงคบเขาปบเนยกลายเปนวา
ตามใจเขาไมสนใจ เขากเลยไมร Patcha: แลววาแกไมเขาใจเพราฉะนนเรากไมแนใจหรอกวาขนตอนทเรา
อธบายนะมนทาใหเดกไมเขาใจหรอวาเขาไมฟงเรา แตหนงคอเขา
ไมฟงเรามากกวา บงเอญเปนหองตวเองดวยความทวาเราเขาใจเขา
วาอานหนงสอบางทเขาใจบางทแกอานเรองนมาแลวขออนญาตไม
เรยนไดไหม กถามตรงๆ กโอเค แตหามคยนะ กเลยทาใหไมบงคบ
คณตองฟง คณตองเรยน ใจดกบเขาแลวกเขาใจในบางคนเดกมน 50 คนไมไดเปนแบบนนหมด อมๆ ตวเขาเองไมรบผดชอบตวเอง
นงฟงไปเรอยๆ ไมคดตาม ไมจด อะไรตออะไรกทาใหหลดไดงาย
มาก Interviewer: ปญหานไมใชเฉพาะ Patcha: ทว ใชไมใชทนหรอก พนฐานของเดกในการรบผดชอบตวเองเนย
มนนอย ถาเปนสมยกอนเนยโอเคเราตองเรยนเราตองหาเขาตวเอง
เวลาทเราไมรเราตองอานเองแตเขาไม เพราะฉะนนเขาคดไมเปน
ตรงนเปนการศกษาทลมเหลวเราไมโทษวาทกคนกอยากจะสอบ
เอนทรานซไดหมดแหละ ตวเขาเองเขาไมเอาชวะเนยเขากแคสงงาน
เขากไดคะแนนเกบเขาไมตองซอม เขาคดแคนนแตเขาไมไดมองวา
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do not use biology, they just need to submit the assignment. They get the points. They just think that, but they do not view that this is the foundation. Interviewer: For further education? Patcha: Yes. It is for living and so on because biology is something very close to us. Like genetics. Do you know it is genetic inheritance? How do you pick your mate? There are reasons that they can use to explain. When they do not mind, I think it is failure. I always tell myself that learning biology is not only for teaching. It can be used in everyday life for caring our body. We can take care of environment. We can explain our friends or students. That is I understand what I teach students.
จะเปนพนฐานท Interviewer: ทสาหรบเขาจะไดเรยนตอ Patcha: ใช การทจะเขาใจในการดารงชวตเรองอะไรตออะไรเพราะชวะน
เปนอะไรทมนใกลตวเรามาก นอยอยางเรองของพนธกรรมน คณร
ไหมวามนถายทอดทางพนธกรรม คณตองเลอกคครองคณตองระวง
ยงไง อะไรอยางเนยมนกมสาเหตทเขาจะเอาไปใชได เหตผลเขาเอา
ใชไดแตเมอเขาไมสนใจเนยมนกเลยมองวามนลมเหลว เพราะ
ตวเองจะบอกกบตวเองเสมอวาอยางเราเรยนชวะเนยเราไมไดเรยน
เพอเอาไปสอนเฉยๆ ตวเองจะบอกเลยวาตองใชในชวตประจาวนเรา
ใชในการดแล
Interviewer: What are the issues you found in your teaching? Pakorn: There is one. It is a continuous issue. From changed system, students learn from outside tutoring schools. I however think they would not get a concept. They see questions. Like, if you remember questions, you do not need a concept. Interviewer: How do you react to this? Pakorn: About learning time, if we do not have sympathy, students will have a hard time. Since some students have already decided they will go to these schools. To entrance these schools, some students do not use physics in exam, I understand that they are wasting time to listen because they do not use it. If you study with me, when you come and you are confident that you will not use biology, you can do other works in the class. However, you need to pass the exam. I help because it wastes students’ time. They can get points from other subjects, spending time on practicing exam, understanding that parts. Helping what I can do. The school has a policy to give students some works. If they have works, they can get points. Not that they do not study and get grade. Since the system now is like that.
Interviewer: อาจารยพบปญาหาอะไรบางในการสอน Pakorn: มนกมนะ มนเปนเรองสบเนอง อยางจากระบบทมนเปลยนไป เคา
จะไปไดมาจากโรงเรยนกวดวชา แตผมวามนไมคอยเขาใจ concept อะ มนเหนโจทยกทาโจทยได คลายๆกบวา จาโจทยได
แตวาไมเขาใจ concept Interviewer: แลวอาจารยมวธปรบแกอยางไรบางคะ Pakorn: กคอถา อยางเรองเวลาเรยนถาเราไมเหนใจกนเนย นกเรยนจะลาบาก
เพราะอยางเดกบางคนเคาตดสนใจแลววาจะไปเรยนคณะน คณะน
บางคนกไมอยากใชฟสกสสอบ เรากเขาใจเขานะวามนเสยเวลาทเคา
จะตองมานงฟง เพราะวาเคาไมตองใช แตถาสาหรบผมเนยถาคณ
เรยนกบผม ถาเดกมา แลวคณมนใจอยแลววาคณไมไดยนชวะใชมย
คณจะเอางานอยางอนอะไรมาทาในหองกได แตคณตองเอาตวรอด
นะ เวลาสอบกตองสอบใหผานนะ ตองชวย ผมชวย เพราะวาเราจะ
มายอใหเดกนงฟงอะไรทเคาไมตองใชเนย มนกเสยเวลา เคา เสย
อะไรตางๆ แทนทเคาจะไปเอาคะแนนอยางอน กเอาเวลาไปทา
โจทยตางๆ พยายามเหนใจในสวนนน ชวยไดเทาทชวย โรงเรยนกม
นโยบายวาใหสงงานเดกบาง ถาไมมาแลวมงานกใหคะแนนไป
ไมใชไมมาเรยนเลยแลวกไดเกรดไป เพราะวาระบบตอนนมนเปน
แบบน”
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Part III: The Impact of the Designed Learning Materials
on Students’ Understanding of Multiple Models of the Gene
In this section, I examine students’ understanding of multiple models of the gene to
evaluate the impact of designed learning materials. The expected outcome from the learning
materials was that students would establish an integrated knowledge of multiple models of the
gene and an improved ability to apply them in explaining genetic phenomena fruitfully. Based on
teachers’ suggestions, three to five students were selected from each observed classrooms to
participate in individual interviews after classical genetics and molecular genetics classes. The
student participants were eighteen students from the five classrooms with the intervention and
three students from the control classroom. I did not collect the data of students’ understanding
before the intervention, under the assumption that the results would be similar to the baseline
established in my master’s thesis study (Auckaraaree, 2009). The student interviews were coded
with developed codes based on the teacher analysis.
Overall, the analysis from this study revealed that, after intervention, many students
constructed a coherent understanding of multiple models of the gene and could solve genetics
problems requiring both models. Further, the students developed an understanding of the
relationship between genes, proteins, and phenotypes. Although these results require further
study, they suggest that the designed learning materials have a positive effect on students’
understanding of, and ability to apply, multiple models of the gene.
Result in this section are divided into five parts: a) students’ conception of the gene; b)
students’ use of multiple models of the gene; c) the cross-case analysis of students’ conception of
multiple models of the gene; d) students’ attitude toward learning genetics; and e) the cross-case
analysis between student knowledge and teacher knowledge and practice.
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Students’ Conceptions of the Gene
In order to explore their knowledge after instruction, student participants were asked to
describe and draw pictures to illustrate their ideas of the gene. As with the analysis of teacher
results, this analysis examined the default models that students chose in order to describe the
meaning and the function of the gene; in other words, it discloses salient models in students’
minds that are most likely to govern their thoughts about the gene. Judging from the results from
both verbal descriptions and visual representations, students mostly applied the classical model
in their responses.
Description of the gene. The analysis showed that the students demonstrated multiple
ways to conceptualize the gene, including as a unit of inheritance, a DNA section, and a
nucleotide sequence. Students’ responses were coded into the classical model group and the
molecular model group (see Table 14). Thirteen out of eighteen students (approximately 72%)
defined the gene according to the classical model; most identified the gene as “a thing that
transfers genetic inheritance”. In contrast, five out of eighteen students (approximately 28%)
defined the gene according to the molecular model; they identified the gene as “part of DNA
sequence that controls gene expression”. These students were SRM3-Tanya, SBS11-Chakrit,
SBS12-Jate, SBD13-Ritda, and SBD14-Maha. In the control group, two students described the
gene according to the classical model and the others according to the molecular model. Note that
it was not possible to test differences between the control group and the experimental group in
terms of the numbers due to the limited sample size of the control group.
As with the results from the teachers, the results from students showed that they
associated the gene function of each model with particular genetics domains. The function of the
gene according to the classical model was to passively transfer genetic traits. The function of the
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Table 14
Examples of Students’ Descriptions of the Gene and the Function of the Gene
Number of Students (N=18) (%)
Examples of Students’ Responses to “What is a gene? What is the function of a gene?
Classical Model 13 (72.22) SRC06-Parnlaka:
A gene is a unit of genetic inheritance. It brings traits from parents to offspring. The function is that a gene transfers genetic traits.
Parnlaka: ยนคอหนวยของพนธกรรมทมนจะเปนตวทมาลกษณะของพอแมออกไป
แสดงในรนลก หนาทกคอยนกถายทอดลกษณะทางพนธกรรม
SRC08-Nawaporn: A gene is a unit of genetic inheritance in DNA. The function is to bring genetic materials from the parents to offspring.
Nawapon: ยนเปนหนวยพนธกรรมอยใน DNA หนาทเปนตวนาสารพนธกรรมจาก
พอแมมาสลก
SBS10-Niran: A gene is using protein of chromatin. No. chromosome. To coil together with histones, DNA (sic.). It will be a small unit having gene inside. It is characteristic inside that. And, each gene is allele. There are dominant or recessive inside itself.
Niran: Geneกคอการนาตวโปรตนของโครมาตน เอย chromosome ให
มาพนมารวมกน ฮสโตร DNA มนกจะกลายเปนหนวยยอยทจะม gene อยขางในคอเปนลกษณะอยขางในนนแตละ gene กจะเปน allele เนยจะมเดนหรอดอยอยในตวมนเอง
SBP18-Kawin: A gene is a thing transferring genetic traits from generations to generations. The function of it is a transferor of genetic traits.
Kawin: ยนเปนตวสงตอลกษณะทางพนธกรรมจากอกรนไปอกรนแลวเออ กคอ
หนาทของมนคอเปนตวสงตอลกษณะทางพนธกรรม
2 (66.67) Control group
SBV20-Yot: A gene inside chromosome that has DNA packaged inside. It is a thing transferring genetic traits from generation to generation.
Yot: Gene อยใน chromosome เปนขางในบรรจ DNA ซงเปนสงท
ถายทอดลกษณะพนธกรรม จากรนสรน
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Tabel 5.1 (continued)
Number of Students (N=18) (%)
Examples of Students’ Responses to “What is a gene? What is the function of a gene?
Molecular model 5 (27.78) SRM3-Tanya::
What is it? Ok. I viewed that a gene is a genetic material inside cells of all living organisms. It functions in storing genetic information like genotype or phenotype.
Tanya:: มนคออะไร ok หนมองวา gene มนเปนสารพนธกรรมทอยใน cell ของสงมชวตทกชนด กคอมนทาหนาทเกบรหสขอมลทางพนธกรรม พวก
ลกษณะ genotype หรอ phenotype ไปดวย SBS11-Chakrit:
Actually, for this word. I think it is difficult to explain…The word gene, g-e-n-e, is described differently in each period. It is a unit controlling the genetic expression. In the past, Mendel used knowledge of prob. (probability); it is prob and stat. Explaining to this point. Later, they discovered it is complicated than that. We cannot use math to directly explain. Like I said, it is an informational unit controlling genetic expression. The function, the function. If I described based on books, it is a thing that determines genetic traits such as protein synthesis. It brings about many things from fingers, bones, hormones, and everything.
Chakrit: จรงๆ คาน ผมพดตรงๆ วา อธบายยาก…คอ เคา gene g-e-n-e เนย ไมวาในยคสมยไหนเคาจะแบบใหความหมาย describeมาในทศทาง
เดยวกนวา เปนหนวยทควบคมการแสดงออกทางพนธกรรมแตใน
สมยกอนmendel ใชความรทางดาน prob นะคบนะ เปน prob and stat มาอธบายตรงน ภายหลงแลวพบวามนลกซงกวานนใช math อธบายโดยตรงตวไมได อยางทวาละครบ คอเปนหนวยขอมลท
ควบคมการแสดงออกทางพนธกรรม กหนาทคอ หนาทเนย ถาเกดวาพด
ตามตารานะครบคอเปนตวท กาหนดลกษณะทางพนธกรรมเชนการ
สงเคราะหโปรตน ซงมนจะนาไปสหลายๆ อยาง ตงแต นวมอ กระดก ฮอรโมน อะไรทกอยาง
SBD13-Ritda: A gene is a part of DNA that has protein synthesis. The function of a gene is a part that can be divided and can be expressed. The important thing is if we don’t have gene expression, a trait will not be expressed.
Ritda: ยนคอสวนของ DNA ทมการสงเคราะหโปรตน หนาทของยน กเปน
สวนทใชในการแบงตวมาเองแลวกแสดงออก สวนความสาคญ ถาเราไมม
ยนแสดงออก ลกษณะกจะไมแสดงออก
1(33.33) Control group
SBV21-Panee: A gene is a sequence part that is used to control genetic trait, how it will be expressed outside. A gene may control DNA (sic.) to determine how the gene will be expressed.
Panee: ยนคอสวนลาดบทใชในการควบคมลกษณะทางพนธกรรมทจะแสดงออก
ภายนอกวาเปนยงไง ซงยนนาจะควบคม DNA อกทหนงวาจะกาหนด
วาจะไดยนแบบไหน วาแสดงออกมายงไง
Note. Red text indicates the classical gene model. Blue text indicates the molecular gene model.
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gene according to the molecular model was to determine genetic traits through protein synthesis
or to store genetic information. Compared to the students’ responses, the teachers’ responses in
the molecular group showed a better understanding of the active and continuous nature of the
molecular model as, for example, “regulating the synthesis of matter”. The responses by the
students in the molecular group were limited to determining what versions of traits are
expressed.
Although one of the goals of the designed learning materials is to promote students’
development of the molecular model, a majority of students maintained the classical model as
their most salient idea of the gene. Importantly, students did not conceptualize the gene as a
sequence of instructions. However, compared to the results from my master’s thesis, the
percentage of students who develop an understanding of the molecular model after intervention
increases considerably from 10% to 28%. This increase in the salience of the molecular model
indicates that the tools were effective in promoting the most widely model used in current
science.
The previous studies deficiently determine students’ conception based on a set of
interview questions. In fact, the results in my study showed that students conceptualized the gene
in many ways depending on contexts of the problems. In this study, the students answered the
follow up questions eliciting the molecular model, such as “What is a genetic code?” The
analysis revealed that most of the students in the default classical model group were able to use
an understanding of the molecular model when they responded to other interview questions
(SRM2-Bonmee, SRM5-Ratana, SRC6-Parnlaka, SBV19-Wally, and SBV-20 Yot). For
example, SRM5-Ratana could describe the meaning of genetic code. However, the students in
the molecular model group elaborated the genetic code in a more scientifically accurate manner,
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as shown in SBD13-Ritda’s quotation. He compared a genetic code to a language in order to
explain the notion of the gene as a sequence of instructions. The next section, on the use of
multiple models of the gene, offers a detailed analysis exploring whether students developed the
molecular model as independent from or integrated with the salient classical model.
The classical model group Interviewer: You said a gene is inside DNA. How is it expressed to traits you can see outside? Ratana: It is turned into an enzyme functioning for curling hair or double eye lid. Interviewer: How it become to enzyme from DNA? Ratana: Transcribing codes. Interviewer: Explaining more. Ratana: It likes DNA strand, right? There will be things, like that. Transcribing codes and translating. See what strands we get and then express. Interviewer: You talked about codes in DNA. Can you explain more what you mean by that? Ratana: It (genetic code) is AGTC, something like that. Then, they are like they are in mRNA before, right? (sic.) Then, it translated into DNA, translating DNA into enzyme. To indicate what enzyme, this is according to the coding strand.
Interviewer: ทวายนอยในDNA แลวมนแสดงออกเปนลกษณะภายนอกไดยงงย เหมอนกบสผวขาวดา Ratana: มนกจะมการกลายมาเปนเอนไซม เพอทางานเปนผมหยกศกหรอวาตา
สองชน Interviewer: แลวจาก DNA มนมาเปนเอนไซมไดยงงย Ratana: กถอดรหส Interviewer: อะ ชวยอธบายนดนงทเราพอจะจาได Ratana: กเหมอนกบ เปนสายของ DNA ใชมยคะ แลวกจะมเปนตวอะไร
ยงงอะคะ แลวทนกถอดรหส แปลออกมา เอามาดวาเปนสายอะไรอย
บาง แลวกแสดงลกษณะออกมา Interviwer: นองพดถงรหสในดเอนเอ อยากใหนองอธบายความหมายเพมเตมคะ
Ratana: เปนตว AGTC อะไรยงงอะคะ แลวกแตละตวเหมอนอยใน mRNA กอนปาวคะแลวกมาแปลเปน DNA แลวถอดรหส DNA เปนเอนไซมแลวมาดวารหสสายตวนเปนเอนไซมอะไร
The molecular model group Interviewer: Can you explain the meaning of genetic codes? Ritda: What is a genetic code? A genetic code is like language. It tells us what to express. However, this language is from 4 letters in DNA. The total is 5 letters that are A,T, C, G, and U. Three letters are needed for composing this code. It may be random. Whatever letters. If
Interviewer: นกเรยนชวยอธบายความหมายของรหสทางพนธกรรมใหฟงหนอยคะ
Ritda: รหสพนธกรรมคออะไร รหสพนธกรรมกคอ เหมอนกบวา คลายๆภาษา เปนสงทบงบอกวาจะแสดงออกอะไร แตวาภาษาเนยมนออกมาจาก
ตวอกษรประมาณ 4 ตวใน DNA แตทงหมดม 5 ตวนะครบ คอ ATCGU รหสพวกนถาประกอบขน กจะมแคสามตว อาจจะเปน
การสมวาจะเปนตวไหนกไดแลวแต ถาสมมตเราได สมมตเราสมมา C G T รหสพวกนถาประกอบขนกจะเปนคาๆหนง หลงจากการแปล
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Drawings of the gene. The students were also asked to illustrate their ideas of the gene
with drawings. Drawing the gene shows how students used visual representations to explain this
abstract idea. The data is also used to triangulate the findings from students’ descriptions of the
gene.
As expected from their definitions, in depicting the gene, a majority of students applied
representations belonging to the classical model (see Table 15). Most students (approximately
61%) who were categorized into the classical model group in the above analysis drew
representations of the gene according to the classical model, most frequently with a picture of a
chromosome indicating the locus of the gene. Some of the pictures depicted a string of DNA
packaged in chromosomes. In the control group, all three of the students depicted the gene
according to the classical representations, including SBV21-Panee, who previously defined the
gene using the default molecular model. Only two students, SRC9-Anna in the classical group
and SRM3-Tanya in the molecular group, exclusively drew representations depicting the
molecular model as a DNA sequence. The student results contrasted with the teacher results,
since most teachers depicted the gene using only molecular representations. One explanation
could be that students are more familiar with classical representations. As a result, most students
promptly visualized the gene at the cellular level instead of at the molecular level, which could
hinder their reasoning regarding biochemical interactions in genetic phenomena.
we assume and we sample CGT, this code will be one word. After translation, we get one amino acid. Mostly they connect to others. During translation, amino acids will connects. Then, they are changed later (sic.). Next, expression.
รหสเรากจะไดกรดอะมโนอกหนงตว ซงสวนใหญกจะไปตอกน เพราะวาเวลาเราแปลรหสอยางเนย กจะตอกน แลวกจะไปปรบเปลยน
ภายหลง แลวกแสดงออก
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Table 15
Students’ Drawings of the Gene
Classical model representations Molecular model representations Multiple representations
Note. Students’ drawings of the gene captured from the interviews. Colors represent models that the students had from the previous analysis on verbal descriptions. Red text with dotted underline indicates the classical model group. Blue text with underline indicates the molecular model group
SRS10-Niran
SRM5-Ratana SRC6-Pornlaka
SRC7-Sittichok SRC8-Nawapon
SRC9-Anna
SBP16-Somchai SBP17-Vit SBP18-Kevin
SBV19-Wally SBV20-Yot
SBS11-Chakrit
SBS12-Jate
SRM3-Tanya:
SRD13-Ritda
SBD14-Maha
SBD15-Piya
SRM1-Anada SRM2-Bonmee SRM4-Davis
SBV21-Panee
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Interestingly, five out of eighteen students in the experiment group (approximately 27%)
gave multiple representations of the gene that accorded with both the classical representation and
the molecular representation. The students drew multiple representations of classical
chromosomes linked to a DNA ladder or a DNA sequence. Only SBS11-Chakrit specifically
indicated symbolic classical models by writing alleles “A” and “a” representing the locus of a
gene in the form of DNA inside homologous chromosomes. Based on the previous analysis, four
students held the default molecular model and only SBD15-Piya held the default classical model.
This suggests that students who used the molecular model as their default definition of the gene
were more likely to use multiple linked representations of the gene together than the students
who used the classical model. These multiple representations regularly are used separately
without connections. Therefore, the students’ ability to draw linked multiple representations
indicates that they had some awareness of how the two gene models were connected.
Students’ Use of Multiple Models of Genes
This section reports students’ ability to connect multiple models in with linked
representations. I propose that the designed learning materials using multiple linked
representations help students to connect gene models with ease and to apply them in contexts, for
a more complete understanding of genetics. The analysis centered on how the designed learning
materials supported students’ comprehension of the gene in integration.
The analysis drew from three sets of interview questions used to document how students
applied models in defined and undefined genetic domains. The purpose of these sets of questions
was not only to provide evidence of student understanding but also to improve the designed
learning materials. Only when the students were asked questions C, using both models, were
they able to demonstrate their capacity to connect models.
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1) Questions using either individual or multiple models. These general questions about
causes of genetic traits were not specific to any one model. Students could apply one
particular model or both models to explain scenarios created by students.
2) Questions using individual model. Students participated in solving genetics problems
related to the classical and to molecular genetics domains separately. These problems
were similar to questions students answer in the classroom or on exams. Each
problem requires only one particular model in order to solve.
3) Questions using multiple models. This set of questions aimed to elicit students’
understanding of both models and their level of connections between the models, both
without given genetic contexts (Figure 13) and with given genetic contexts (see
Appendix). The questions were based on the multiple linked representations strategy
used in the designed learning materials
1) Questions using either individual or multiple models. The students responded to
questions that did not require a particular gene model to explain the scenario. Students were
asked to list genetic and non-genetic traits and then to describe what classified particular traits as
genetic. The results indicated that students did not make any explicit connections between the
models in answering these non-structured questions. This suggests that students tended to apply
the multiple models separately even after the intervention. A majority of students offered
explanations based on the classical model, while others explained based on the molecular model.
Both types of explanations were scientifically accurate.
For the first question, the results showed that all students were able to identify genetic
and non-genetic traits correctly. Most students gave examples of eye color, height, color
blindness, and blood type. The students raised questions regarding whether diseases such as
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cancer and heart disease could be counted as genetic traits, due to their complex nature. These
traits are examples of multifactorial inheritance disorders caused by a combination of small
inherited variations in genes, often acting together with environmental factors. What constitutes a
genetic trait has become difficult to define due to the advance of current genetics knowledge.
The next question students responded to was “Why do you think the mentioned trait is a
genetic trait?” Most students offered scientific explanations using the classical model to explain
how they differentiated between genetic and non-genetic traits. Thirteen out of eighteen students
(approximately 73%) provided the reason that “a genetic trait is something being transferred
from parents”. All students in the control group were coded in this category. By contrast, five out
of eighteen students (approximately 27%) reasoned within a molecular genetics domain; the
statements using mutation and gene expression were coded into this category (SRC9-Anna,
SBS10-Niran, SBS11-Chakrit, SBS12-Jate, and SBD13-Ritda). Except SBS10-Niran, these
students had defined the gene using the molecular model. A majority of students applied the
default model they had used to define the gene in earlier questions, supporting the idea that this
was the most salient model for each of those students, and the one that they would naturally use
when the question did not require a particular model.
The excerpts below exemplify differences in students’ reasoning with the different
models. Using the classical model, Tanya explained a genetic inheritance of anemia by passing
dominant and recessive genes. Using the molecular model, Chakrit described a mutation in DNA
sequences causing malfunction proteins in sickle cell anemia.
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Reasoning based on knowledge in classical genetics domain
Interviewer: What are the criteria you use to define genetic and non-genetic traits? Tanya:: If it is genetics. I viewed that it can be transferred to next generations. If it is not, it stops at those individuals. It may occur again, but that will be happen when we get outer factors or inner factors. However, this could not be continuously transferred. … Interviewer: Anemia that you mentioned is also a genetic trait. Can you explain how it happens? What is the cause of this disease? Tanya:: The cause is that my granpa has anemia that expressed immediately. It was abnormal. My mom has anemia so I have anemia. That’ why first I understood that this trait in my blood line should be due to dominant gene. That’s why it expresses. My dad may be. May carry a recessive gene of anemia. When meeting together, my family has this in every generation. … Interviewer: Then. Can you elaborate little more how it actually happens at the cell level? How could we transfer traits to offspring? … Tanya:: Hmm. I think first chromosomes are diploids or 2n. Then, in cell division, cells are divided. Meiosis is sex cells to haploid. There will be only one cell left. After that, cells from dad and mom each with one n will meet others. Getting 2n. Offspring will not get exceed chromosomes. It makes us get half from dad and another half from mom, having trait together. Then, if some genes containing diseases, abnormal. When it combines together. Some recessive genes combine together; it will express like dominant gene. Express in that individual.
Interviewer: อม ok เมอกเราพดมานดนงแลว พอยากจะถามวา แลวเราใชอะไรเปน
กฎเกณฑในการแบงวา อนน นาจะเกยวของกบพนธกรรม อนนไม
เกยวของ Tanya:: กคอ ถาเปน ถาเปนทางพนธกรรมหนมองวา มนสามารถถายทอดมาสรน
ลกหลานได แตถามนไมใช มนกจะหยดทตวบคคลนน เพยงแตอาจจะ
เกดขนไดอก เมอ เมอเราไดรบปจจยภายนอก หรอวา ปจจยภายใน เพยงแตวา มนไมสามารถเกดขนแลวถายทอดกนอยางตอเนอง … Interviewer: โลหตจางกเปนโรคทางพนธกรรม เปนโรคทเกยวของทางพนธกรรม อยากใหเราอธบายนดนงวา เออ แลวมนเกดขนไดยงไง ทาไมเราเปนโรคน อะไรเปนสาเหตของโรคน Tanya:: ออ สาเหตของโรค คอ คณตา เปนโลหตจางทแสดงออกเลยอะคะ วา ตว
น ตวนผดปกต เสรจแลวคณแม คณแมกเปนโลหตจาง หนกเปนโลหตจาง แตวา หนกเลยเขาใจวา กคอเขาใจวา ตวโลหตจางทเปนสายเลอดของหน
มนเปน gene เดนเลยนะคะ มนกเลยแสดงถายทอดมา อกฝงนง คณพอ
อาจจะเปน นาจะม gene แฝงของพวกโลหตจางมาดวย พอมาเจอกนก
เลยทาใหของหนออกอาการกนทกรนเลย … Interviewer: อะแลวทน อยากใหเราอธบายเพมเตมอกนดนงวา ทมการถายทอด gene จากรนนงมาสอกรนนง อยากใหเราอธบายเพมเตม วา แลวจรงๆมนเกด
อะไรขน ในระดบ cell ทาไมเราถายทอดลกษณะนไปสลกได … Tanya:: ออ กคอ กคอ ทหนเขาใจกคอ เปนวา chromosome ตอนแรกจะ
เปน ดพอลย เปน 2n เสรจแลวมนจะทาการ มนจะแบงเปน ไมโอซส เปนcell สบพนธ เปน เฮบพอลย กจะเหลอ แค cell เดยว เสรจแลว
ทางฝงพอกบแมกจะมอยางละ n พอมาเจอกน กจะได 2n พอด เดกกจะ chromosome ไมเกน มนกจะทาใหเราสวนหนง ครงหนงมาจากพอ ครงหนงมาจากแม มลกษณะรวมกน ทน ไอตว gene บางตว ทเปน
พวกโรค เปนความผดปกตตดมากบ gene กพอมาเจอกน บางตวเปน gene แฝง มาทงค พอมาเจอกน กเลยแสดงออกเปน gene เดน มน
เลยแสดงออกทบคคลนน
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Reasoning based on knowledge in classical genetics domain
Interviewer: Can you please give an example of genetic trait? Chakrit: Yep. Sickle cell anemia. Interviewer: Sickle cell anemia. What do you think is the cause of this disease? How is it happen? Chakrit: It is abnormality at the gene level more than at the chromosome level, because it is due to protein synthesis giving wrong structure. Therefore, cell is malfunction as well. Interviewer: Wrong structure. Hmm. Do you think in the normal people still has a chance to have this gene? Chakrit: At some levels. Yes. Since, nowadays there are many things around human that could cause mutation such as magnetic and electronic fields. These are the minimum. If the causes are from outside will effect another level. Mutation from chemicals from carcinogens. These are causes. Interviewer: How is this change bringing about the disease? Chakrit: Hmms. It is expression of DNA through mRNA and proteins. DNA is changed to mRNA strand and expressed to a protein, using mRNA as template. Proteins express and tell how will we look like.
Interviewer: อยากใหนองลองยกตวอยาง โรคทางพนธกรรมมาสกขอนง Chakrit: คบ Sickle cell anemia Interviewer: Sickle cell anemia แลว นองคดวา อะไรเปนสาเหตของโรคน มนเกดขนไดยงไง Chakrit: คอ จะเปน เกดความผดปกตในระดบ gene มากกวาทจะเปน chromosome คบ เพราะวา เกดจากการสงเคราะหโปรตนผด
รปแบบ ทาใหพอออกมาเปน cell จะผดปกตไป Interviewer: ผดรปแบบ อม แลวนองคดวา ในคนปกตหนะคะ ในคนปกตมโอกาสทจะ
ม gene นอยม ย Chakrit: กมในระดบนงนะคบ เพราะวา หลายๆ อยางเพราะวาๆ นบวนขนไปเนย มนษยมอะไรทอยใกลตวแลวกอเกด อยางสวนมากอยางตาสดกคอ
สนามแมเหลก กบสนามไฟฟา อนนเปนอยางตาเลยคบทผานตว แลวถา
เกดวาจากขางนอกอก effect กมในระดบนงแลว แลวก mutation จาก chemical จาก คาซโนเจน ไอๆ กมอยในสวนนง Interviewer: แลวการเปลยนแปลงนสงผลออกมาเปนโรคนไดอยางไรคะ
Chakrit: ออ เปนการแสดงออกของ DNA โดย mRNA และโปรตน DNA จะถกแปลงใหเปนสาย mRNA และแสดงออกโดยใช mRNA เปน
ตนแบบเพอสรางโปรตน โปรตนทไดกจะแสดงออกเปนวาเราจะเปนยงไง
2) Questions using individual model.The analysis documented how the students
applied the gene models to solve genetics problems, similar to those they normally practiced in
the classroom, in which the appropriate model was indicated by the structure or content of the
problem. When solving either classical genetic problems or molecular genetics problems,
students applied only one particular model constructed in that domain. The results showed that
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the students employed the two models separately without addressing another model in their
answers.
Classical genetics problems. The students were asked to predict the genotype and
phenotype of a given complete dominant trait (see Appendix). Most of the students showed
capability in solving classical genetics. Most students successfully explained the function of the
dominant allele over recessive traits and calculated correct probability of phenotype. Few
students needed guidance to proceed to the problem solving. For example, the students could not
identify a ratio of a dominant allele and a recessive allele in the population because a given ratio
is not absolute like samples they learned in the classrooms. Scientific terms related to the
molecular model, such as “base sequences” related to discourse in molecular genetics area, were
not found in students’ explanations.
Molecular genetics problems. Students were asked to transcribe and translate a given
DNA sequence to polypeptide and explain the underlying molecular processes. Students also
were asked what happened to a protein after protein synthesis in order to bring about phenotype.
The results showed that half of the students could translate the sequence correctly. However,
some students had difficulty in solving problems and elaborating molecular processes of protein
synthesis, in particular those who used the classical model as their default. Most students
struggled to explain the function of the protein after protein synthesis. Scientific terms related to
the classical model, such as “genotype”, related to discourse in classical genetics area were not
found in students’ explanation.
3) Questions using multiple models. One prominent strategy of the designed learning
materials is linked multiple representations. This strategy requires students to make explicit
connections between the classical and the molecular models as well as to apply both models in
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integration in order to solve genetic problems. The analysis in this section relied on students’
visual representations, their efforts to link multiple representations in response to a question, and
the explanations they offered in response to a question about gene expression for a color trait of a
flower.
Students’ connections between the classical model and the molecular model were
categorized based on emerging codes from the teacher results: lacking models, separation, partial
connection, and integration.
a) One model. The findings reveal that, even after the intervention, a few students did
not have a sufficient understanding about the molecular model. Three out of eighteen students
from the intervention classroom (approximately 17%; including SRM2-Bonmee, SRM5-Ratana,
and SRC6-Pornlaka) and two students from the control group (including SBV19-Wally and
SBV20-Yot) did not demonstrate sufficient background knowledge regarding the molecular
model.
Due to unfamiliarity with the molecular model, this group of students could not develop
explicit connections between the models of the gene. Furthermore, the students in this group
could not elaborate molecular processes or solve molecular genetics problems, as in the example
shown below. The findings confirmed the results from my master’s thesis that a sufficient
understanding of the molecular model is prerequisite for reasoning in the molecular genetics
domain.
For instance, Yot from the control group conceptualized the gene with only the classical
model. He was confused about how a gene is associated with DNA because a gene is located on
a chromosome, and he could not associate the classical representation with the molecular
representation. Moreover, he misunderstood the picture B of DNA sequence consisting of protein
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instead of nucleotide sequences. When Yot answered a question about how a gene inside the
nucleus is expressed as a phenotype, he incorrectly explained that the gene is expressed through
DNA replication and protein synthesis. He did not realize that these biological processes happen
independently. One possible explanation is that these topics are presented in the same section in
current Thai genetics curricula. His misconceptions concerning the relationships among genes,
proteins, and phenotypes were consistent with those of other students from my master’s thesis.
Interviewer: Could you describe how a gene looks like? Yot: A gene is DNA, right? Interviewer: Yes. Yot: DNA. But, how is it a gene? Interviewer: And where is a gene? How is it related to DNA? Yot: Gene, a gene should be in a chromosome. Interviewer: Where? Yot: I knew now. A gene is inside a chromosome. Interviewer: Where on a chromosome? Yot: Where? It can be everywhere. … Interviewer: What does this picture A mean? Yot: Chromosomes and genes. One gene controls one phenotype. Interviewer: Yes. Capital R and small r. What do they represent? Yot: This one is. Hmm. Dominant gene and recessive gene. Interviewer:
Interviewer: คดวา gene มรปรางหนาตายงไง หรอจากทเราเคยเหน Yot: Gene เหรอ นมน DNA ใชมยครบ Interviewer: คะ Yot: DNA จะให gene เปนไงอะ Interviewer: แลว gene อยตรงไหน เกยวของยงไงครบ DNA Yot: Gene… gene ตองอยใน chromosome ด Interviewer: อา ไหน Yot: รแลว gene กอยใน chromosome Interviewer: อะไหน อยตรงไหนของ chromosome Yot: กอยตรงไหน อยตรงไหนกไดปะ … Interviewer: ภาพนมนหมายถงอะไร ทเราพดอะ ภาพนแสดงอะไรบาง Yot: ก chromosome แลวกม gene gene หนงกควบคมหนง
phenotypeครบ Interviewer: ออ ห แลวไอ R ใหญ r เลก หรอวาอนเนย มนคออะไร Yot: อนนเปน ไมใชครบ นเปนgene เดน อนนเปน gene ดอย Interviewer: อะ ok อะแลวรปท B น แลวอธบายวามนแสดงถงอะไร
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Ok. How about a picture B. What does it mean? Yot: A sequence of protein. I’m not sure. Interviewer: Ok. Interviewer: How about this letters? What are they? Yot: Yes. Interviewer: So, these letters (DNA sequence) is protein, right? Yot: Yes. Interviewer: Ok. I’ll continue then. Do you think pictures A and B are related? How? Yot: How are they related? What? I don’t know. This polypeptide and this one. … (The interviewer explained that the picture B is a picture of DNA sequence.) Interviewer: What is the relationship between the two? Yot: The relationship is, Hmm, this is DNA right. Another one is I think, I cannot explain it.
Yot: ลาดบของโปรตน Interviewer: ออ ห Interviewer: คอทตวอกษร เขยน เนย คอตวอะไร Yot: คอ โปรตน ครบ Interviewer: อะ ตวอกษรทเขยนคน คอ โปรตนใชมะ Yot: ใชครบ Interviewer: อม แลวพถามตอวา รปแรกกบรปทสอง มนมความสมพนธกนมย มน
เกยวของกนยงไง Yot: มนเกยวของกนยงไงเหรอ อะไรเหรอครบ ผมไมคอยแนใจ สวนของ
polypeptideอนน
… Interviewer: อะไรคอความสมพนธระหวางสองรปนคะ
Yot: ความสมพนธกนกคอ ออ กคอ ไอนคอ DNA ใชมยครบ DNA รสก อนนง ออ DNA เอออธบายไมถกอะ
b) Separation. After instruction, three out of eighteen students in the intervention group
(approximately 17%; including SRM1-Ananda, SRC8-Nawapon, and SBP18-Kawin) applied the
classical and the molecular models independently, each according to its domain. One student
from the control group, SBV21-Panee, who understood the default molecular model, showed
separated connection. This group of students never used both models to answer one question.
Although the students illustrated an understanding of the molecular model, they did not illustrate
explicit connections across multiple models.
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c) Partial connection. Five out of the eighteen students (approximately 28%) in the
intervention group demonstrated partial connection by linking a nucleotide sequence in a DNA
strand to the locus of a gene on chromosomes. The students coded in this group were SRC9-
Anna, SBD14-Maha, SBD15-Piya, SBP16-Somchai, and SBP17-Vit. In order to connect
multiple representations, they explained that a DNA sequence is located in chromosomes in
cells, as shown in the excerpt below. The students established connections by recognizing the
structural relationship between different biological entities, but they did not link them together
functionally.
Interviewer: You talked about genes, DNA, and chromosome. What do you think are their relations? Anna: I think a gene is on a chromosome. A gene may be a DNA. Interviewer: Can you draw a picture of what you described? Anna: Drawing from a chromosome? I have to ask first if a gene is DNA, right?. Interviewer: Yes. Anna: This is a chromosome. A Gene is inside a chromosome. When we separate from a gene, a gene is DNA, right? Separating into a strand. Then there is a protein stand coiled outside. And there is something else on here. … Interviewer: Ok. Can you describe what the picture A mean? Anna: The first one is a chromosome. Interviewer: What do the letters or bars mean? Anna: It is a location on chromosome. This one is a
Interviewer: อะ เราคดวา เมอกเราพดถงยน โครโมโซม DNA เราคดวามนม
ความสมพนธกนยงไง Anna: หนคดวายนอยบนโครโมโซม ยนนาจะเปน DNA Interviewer: สมมตวาใหลองวาด วาดวาเราคดวาเปนแบบน Anna: วาดตงแตโครโมโซมเหรอคะ ตองถามกอนวา ยนนคอ DNA ใชมย
คะ Interviewer: ใชๆ Anna: อนนโครโมโซมนะคะ เสรจแลวยนอยบนโครโมโซมคะ แลวเมอเรา
แยกจากยน ยนกคอ DNA ใชมยคะ พอแยกออกมาเปนสาย คะมนก
จะมเปน พอแยกออกมาอกกจะเปนอนน มนจะมสายของโปรตน พน
รอบนอกคะ แลวกจะมอะไรไมรอยบนน … Interviewer: เออ แลว พอยากใหนองลองทายวาภาพแรกหมายถงอะไร Anna: ภาพแรกกคอ โครโมโซมคะ Interviewer: แลวตวอกษรทแสดงหรอขดๆนนหมายถงอะไร Anna: กคอตาแหนงบนโครโมโซมคะ อนนกจะเปนยนแทอะคะ อนนกจะเปน
ยนดอยอะคะ Interviewer:
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dominant gene and this one is a recessive gene. Interviewer: How about the second picture? Anna: The second picture is a gene transcribed from a chromosome (sic.). This one is from DNA and two strands of polynucleotides. Interviewer: What do these letters refer to? Anna: Genetic code. To build a protein. It will be a system later. Interviewer: Ok. Do you think there are any links between these pictures? Anna: I think this picture B should be on the highlighted part here. A gene is inside a chromatin in this part.
แลวรปทสองละคะหมายถงอะไร Anna: รปทสองนกเปนยนทถอดมาจากโครโมโซม อนนมาจาก DNA แลว
มสายโพลนวคลโอไทล 2 สาย Interviewer: แลวตวอกษรตรงนแสดงถงอะไร Anna: รหสพนธกรรม จะเปนทเอาไปประกอบเปนโปรตนตอไปนะ วามนจะ
เปนระบบอกท Interviewer: ok แลวนองคดวาภาพสองภาพเนย มนมความสมพนธกนรเปลา Anna: ภาพนนาจะอยบนสวนทเคาเนนตรงน Gene กจะอยใน โครมาตน ในสวนน
d) Integration. Interestingly, the results suggested that the designed tools successfully
fostered students’ integrated knowledge of the multiple models of the gene. Seven out of
eighteen students from the experimental group (approximately 39%) could construct explicit
connections between the two models after the intervention, while no student from the control
group could make these connections. The students coded in integration group applied two
models concurrently in one explanation within situated contexts. This suggests that when
students engaged in interpreting multiple linked visual representations within genetics contexts
in the activities, they could intellectually integrate their conceptions of the gene models. The
following cases illustrate students’ integration between the models.
Note that some of the students in this group also demonstrated partial connections during
the interviews; they sometimes made partial and sometimes more complete connections. These
students’ responses were coded at the highest demonstrated level.
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Niran. During the interview, Niran demonstrated various levels of connections between
the models when he explained genetic phenomena. Initially he described and drew the gene
according to the classical model. In the general questions regarding genetic traits, he applied the
classical model and the molecular model separately. When he linked the picture A and the
picture B, he made a partial connection between a sequence of instruction and a section of
chromosome. Yet when he used multiple models in response to the question about the colors of a
flower, Niran applied the classical and the molecular model in integration. He explained how
different genotypes, homozygous and heterozygous, lead to different phenotypes through protein
synthesis. The idea concerning the sequence of instructions, from the molecular model, was
clearly integrated with the idea concerning genotypes, from the classical model. Moreover, Niran
showed a clear and accurate understanding of the relationship between genes, proteins, and traits.
a) Separation Interviewer: You said that there is a transfer to next generations. Could you please explain the process? How does it happen? Niran: Oh. It depends if it is on sex chromosome or on autosome, because. It also depends on if it is dominant or recessive. If it is ‘dominant (English)’, it is dominant trait that can be transferred directly. There is higher probability. Interviewer: You said a genetic trait is related to chromosomes, having alleles and genes. Can you please explain more? How is it expressed to be finger print trait that we can observe? How this happen? Niran: If it is chromosome, it has genes, right? A gene determines ‘the expression (English)’ that is the expression. Determining what proteins to produce, something like that. Determining if protein arrangement is this way, it will translate to this one. Something.
Interviewer: แลวนองพดถงวา มนตองมการถายทอดจากรนสรนอยาง อยากใหนอง อธบายแบบถงกระบวนการทมนเกดขน วามนเกดขนไดยงไง Niran: ออ กขนอยกบวา มนอยบน chromosome เพศ เปน autosome นะคบ เพราะวา ถาขนอยกบวามนเปน dominant หรอเปน recessiveดวย ถาเปน dominant กคอ จะเปนลกษณะ
เดนทถายทอดโดยตรง แลวกมโอกาสเกดไดมากกวา Interviewer: ลกษณะทถายทอดทางพนธกรรม มนอยบน chromosome ม allele ม gene อยากใหนองอธบายเพมเตมวาแลวมนถกแสดง
ออกมาไดยงไง ถกแสดงออกมาจนเราเหนเปนลายนวมอ เปนลกษณะ
ภายนอกอยางเนยคบ มนเกดไดยงไง Niran: กถาเปน chromosome กจะม gene ใชมยคบ gene กจะเปน
ตวกาหนด expression คอการแสดงออกมา ใหกาหนดจะสรางเปน โปรตนออกมา อะไรอยางนคบ กกาหนดวา โปรตน ถาเรยงกนแบบน จะสอถงอนน อะไรอยางงคบ
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b) Partial connection Interviewer: You said that the picture B shows DNA structure. What are the relationships between these pictures? Niran: This one is the arrangement of bases, which is a strand of base pairs. It is double strands, helix. It is coiled inside. It is this part (picture A). It could be dominant allele or recessive allele. Interviewer: Do you think this one coiled inside a chromosome? Niran: Yes. … Interviewer: There is a DNA strand coiled inside here. How do you tell that DNA in the picture B is this highlighted piece ‘R’ in the picture A? Niran: Hmm. We have to uncoil this and use instruments to tell what bases. Scientists named it, this one is T. What is this one? Calculating how they are connected. When it will stop. Stopping at UAA. Where it starts. Then cutting it. Checking sections of chromosomes. For example, seeking what parts in people with right-handed are the same.
Interviewer: ถารปนเปนแสดง โครงสรางของ DNA เนย นกเรยนคดวา มนม
ความสมพนธยงไงกบรปแรก Niran: กอนน เปนการเรยงตวของเบสคบ คอจะเปนเบสคกนเปนสายๆ เปน
สายคกนเปนเกลยวคบ ทขดๆ ตวกนอยเปนอยางเนยคบ มนกอาจจะ
เปน allele เดน allele ดอย กแลวแต Interviewer: นองคดวา มนกคอ ขดตวอยในแทง chromosome น Niran: คบผม … Interviewer: มนมสาย DNA ใชมยคะ ทขดพนกน แลวกอยในเนย แลวเราจะรได
ยงไงวา ตรงน ชนสวนทง DNA แลวทมนเปน เปน R หรอม
บางสวน หรอวา ยงไงอยากใหลองอธบายเพม Niran: กคอ ตอง คลอนนออกมากอนคบ แลวกใชเครองมอในการวดวา มา
บอกวา อนนเปน เบส ซงเรากตงชอ มนกวทยาศาสตรตงชอวา อนน คอ T อนนอะไร แลวกวดดวามนจบตวตอกนยงไง แลวจะหยด
เมอไหร หยดท U A A อะไรอยางเนยคบ แลวเรมตนตรงไหน แลว
กคอ บอกวา ตดออกมาแลว ดวา chromosome แตละแหงมา
เปรยบกนวาเนยมนเปนแบบน มนออกมาเปน สมมตวา คนนถนดมอ
ขวา ของมอขวาดวยกน กเอามาดวา สวนไหนทมนเหมอนกนบาง
c) Integration Interviewer: If a tell you that the DNA that you translated is from an individual having a genotype as homozygous dominant, capital A and capital A. I’m asking do you think a protein sequence of homozygous recessive, small a and small a, will be the same or different? Why? Niran: It depends if it is in homozygous or not, they are on the same position. If they are on different locations, there will be different characteristics. Homozygous recessive and dominant. Then, this one will be different because it will be expressed to different traits.
Interviewer: แลวเออถาอาจารยบอกวาสาย DNA ของคนๆ นนะคะ เปนของคนท
ม genotype แบบ homozygous dominant เปน A ใหญ A ใหญ อะ แลว ครถามวา ถาเกดวา คนทมเออ genotype แบบ homozygous recessive คอ a เลก a เลก เนย นกเรยนคดวา ลาดบของโปรตนของเคาเนย จะมทางเหมอนกนหรอ
แตกตางกนยงไง เพราะอะไรบาง Niran: กขนอยกบวา อนน เปนตวทอยใน homozygous รเปลาคบ เพราะวา ถาสมมตวา อยคนละทกน กเคาอาจจะมลกษณะทเหมอนกนก
ได แตถา อยท เปนอนน คอ แสดงลกษณะของ homozygous recessive กบ dominant พอดแลวอนนกนาจะตางกน เพราะวา มนถงจะมลกษณะทแสดงออกมาแตกตางกน
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Interviewer: What is different? Niran: Everything. Traits, sequences, this one will be different too. I mean proteins will be different. Hmm. It depends if that is related protein. Interviewer: What will happen in case of heterozygous? Assuming there is a capital A and a little a. Do you think DNA sequences of the little a and the capital A will be the same? Niran: Not the same because the small one and the capital one have to be different. No. Wait. Sometimes it may be the same. Interviewer: Do you mean it depends on the types of mutation? In this case, it shows that a structure of amino acid is changed one position. Do you think a structure of the protein will be normal? Will be able to function? Niran: It depends which one it hits. For example, if it is stop codon, the mutation will change to no strands after that. If it is another one, like changing codon but can produce it. Interviewer: In this example, it is changed to Leucine. Do you think how a phenotype will be? Niran: Should be abnormal. Hmm. This one produces a protein. But, this one produces until Leucine. This will be abnormal. It will change to something else. Interviewer: Protein changed? Right? Niran: Yes. Interviewer: There is a genotype, capital A and little a. Do you think it can control producing colors? Niran: Yes, it can because this one is dominant that can control the little one.
Interviewer: อะไรทตางกนคะ Niran: กทงหมดเลยคบ ทงลกษณะ ถารหสตางกน ไอนกจะตางกนไปดวยคบ ออ กคอ โปรตนจะตางกนไปดวย ทาใหเออ ขนกบวา โปรตน นน มน มาเกยวของกบลกษณะนนๆ Interviewer: แลวถาเกดวา เปน heterozygous เออ มนจะเกดขนยงไง ไดบาง สมมตวา อนน เปน เอม A ใหญ A เลก นกเรยนคดวา DNA sequence ของ Aเลก จะเหมอนกบ Aใหญมย Niran: ไมเหมอนคบ เพราะวา ตวเลกไมเหมอนตวใหญกตองไมเหมอน เอย เดยวนะฮะ แลวถาสมมตวา เปลยนแลว บางทกอาจจะเหมอน Interviewer: อา แลวแตวา mutation มนเปนแบบไหนใชมะ แลว เออ สมมตวา อนมไมเหมอนโครงสรางของ amino acid จะเปลยนแปลงไป
ตวนงอา แลวถามวา แลวโครงสรางโปรตนทสรางขนมาไดเนย มนจะม
ลกษณะปกตมย สามารถทางานไดรเปลา Niran: ออ ขนอยกบวา ตวนจะเปน เผอญไปโดนตวไหน อยางเชน สมมตวา อาจจะไปทตวจดน เลยกได คอจะม mutation กจะหยดเลย กคอ สายตอไป กคอจะไมม อกอนนง กคอ สมมตวา ถงแมรหสจะ
เปลยนไปแตกยงจะไดอย Interviewer: เนยมนไดออกมาแคเนย อา แคเลยวซน แลวกมนก อะครถามวา แลว phenotype ของตวเนย จะออกมาเปนยงไง Niran: นาจะผดปกตคบ คอ เออ ยงไงด เพราะวาตวน สงเคราะหไดถงโปรตน
ใชมยฮะ แตตวนหยดแค เลยวซน อนนกจะไมปกตไปเปลยนเปนอนอน Interviewer: โปรตนมนเปลยนไป แลวนบอกวา โปรตนอนถกใชมะ Niran: ครบ
Interviewer: เราม genotype เปน Aใหญ A เลกอยางเนย เราจะ จะ ยงคง สามารถควบคมการสรางสไดอยรเปลา Niran: ไดคบ เพราะถาอนนเปน เออ dominant ใชมยคบ กจะคมตวเลก
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Jate. Jate defined the gene using the molecular model, and then drew multiple
representations to illustrate the gene. He first demonstrated a partial connection by explaining his
drawing of multiple representations of the gene; he linked genes, DNA, and chromosomes
structurally. However, he did not explicitly link these representations to the symbolic
representations of the classical model. When Jate explained underlying biological processes
regarding the expression of flower colors, he used both models in a complementary fashion to
explain genetic phenomena. He could identify that the sequence of dominant gene differs from
the sequence of recessive gene, which leads to a difference in the production of proteins. His
statement clearly showed a coherent understanding of genes, proteins, and traits, and he used
both models in context-appropriate ways.
a) Partial connection Interviewer: How is the gene look like? Jate: This is difficult. From what I know, actually a gene. Actually, a gene (pointing at sequence) and DNA (pointing at DNA) are the same thing depending on the positions of chromosomes. If they are on the same location, they will be genes controlling the same trait. This part that is a gene is from coiled DNA in a chromosome.
Interviewer: Gene มนมรปรางหนาตายงไง Jate: ยากเลย กคอ เทาทเขาใจมากคอ ประมาณวาจรงๆ gene มน มนเปน
จรงๆ gene DNA เปนเหมอนอยางเดยวกนนนแหละ แตวาเปนท
ตาแหนงของ โดย chromosome วา ถาอยตาแหนงเดยวกน มนจะ
เปน gene ทคมลกษณะเดยวกน ไอสวนตรงเนยทมนเปน gene จรงๆกคอมนกมาจาก DNA ทมนขดเปนchromosome
b) Integration Interviewer: This is a gene controlling a function of blue flower. Do you think genetic codons in the yellow flower will be the same with the blue flower?
Interviewer: ตรงนเปน gene ทควบคมลกษณะการทางานของดอกสนาเงน แลวพ
ถามวา ในดอกสเหลองเนยคะมนจะมรหสพนธกรรมเนยเหมอนกบของ
ดอกสนาเงนรเปลา
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Jate: They should be different. Interviewer: How? Because? Jate: Because this one. If they relate to the color. It may be one protein controlling a synthesis of flower color. If they are the same, the produced colors will be the same. Interviewer: So, you are saying due to different sequences of DNA proteins are different. … Interviewer: Then, let talk about the activities. What have you learned from that? Jate: For this activity, it likes a dominant gene having, having a base sequence, having another patterns of DNA sequence. In a recessive gene, there will be another one. This recessive gene controls how the flower color will be. In this case, a recessive gene has a sequence of amino. No. a sequence of DNA, base sequence of DNA differs at one point. This change at one point makes change in a property in synthesis. In protein synthesis, a protein is built to a big structure. If the property is changed, the shape is changed. This one can function as an enzyme synthesizing purple pigment. But, this one cannot synthesize this shape, cannot be enzyme. Cannot produce purple pigment. That’s why it turns to white color. Interviewer: How about in heterozygous? Jate: Heterozygous means that it can produce, because it has a part that can produce protein and the non-function one. It has both, so there is synthesis.
Jate: กนาจะตางกนฮะ Interviewer: ยงไงคะ เพราะวาอะไรคะ Jate: กเพราะวาอนน มนกจะ ถาเกดวา เปนเรองส กคอมนอาจจะไปเปน อาจจะไปเปน โปรตนสกตวนงทไปเหมอนกบไปควบคมการสรางส
ของดอกมนเนยคบ กถาเกดวามนเหมอนกนมนกนาจะไดสทออกมา
เหมอนกนอะไรอยางเนย Interviewer: เพราะฉะนน ตวลาดบ DNA กเลยแตกตางกนทาใหระบบโปรตนมน
ตองแตกตางกนออกไปดวย … Interviewer: ทน พอยากถามวา เราเรยนรอะไรบางจากกจกรรมนน Jate: ถาอนน กคอ กคอ เหมอนประมาณวา gene เดน จะม จะมลาดบเบส จะมลาดบของ DNA แบบนง ใน gene ดอยกจะมลาดบอก
อยางนง gene ดอยอนน กคอจะเปนตวควบคมตอเรองสดอกไรอยาง
เนยคบ อนนกคอตามทสมมตมากคอ gene ดอยเนยจะมลาดบ amino เอย ลาดบ DNA ของลาดบเบส DNA ตางกนตวเดยว ซงไอทตางกนตวเดยวทาให คณสมบตเวลาพอมนไปสงเคราะห พอมน
ไปสงเคราะหโปรตนแลวมนจบเปนโปรตนโครงสรางใหญๆ นมน คณสมบตรปรางมนตางไป ไออนนมน สามารถทาหนาท เปน enzyme สงเคราะห สารสมวงได แตอนน รปรางน สงเคราะห รปรางน ทาได enzyme ไมได กเลยสงเคราะหสารสมวงไมไดเลย
กลายเปนสขาวฮะ Interviewer: อาว แลวใน heterozygous หละคะ มนจะเปนยงไง Jate: Heterozygous ก กคอๆ แสดงวา มนกนาจะสรางไดเพราะวามน
มทงสวนท เอามาสงเคราะหเปนโปรตน ไอทสรางไมได แตมนมทงค กนาจะสงเคราะหได
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Tanya. The interview with Tanya showed an interesting case of the application of two
models in integration. It demonstrated an example of applying both models to explain a scenario
outside the designed learning materials. This supported the conclusion that students’
understanding after the intervention was meaningful and transferable, not limited to phenomena
presented in the activities. She considered genetics knowledge as important to understanding her
own anemia, and she applied functions of both models in a complementary fashion to explain
genetic phenomena. This serendipitous example supports one of the original premises of this
research: that the application of genetics knowledge in authentic problems requires the use of
multiple models of the gene to explain complex and personally relevant genetic phenomena.
Interviewer: Why do you have to learn genetics? What is the benefit? SRM3-Tanya:: What is the benefit, right? I view that genetics is the subject. We learn about genetics and genetic materials in our body that passed to next generations. Therefore, I think it can tell. How to call it. Solve the problem about genetic disease. I see this issue because. For example, I have anemia and thyroid. First, I wonder why. Because my parents don’t have it. I look, look at the line. Oh, my grandfather has it. It is liked my mom has hidden gene and my dad has hidden gene, so I have the disease like this. Anemia has a change of protein at location 6. Like that. The structure is different from other people. I learn more about myself. I know the symptom, characteristics and why it happens.
Interviewer: ทาไมนกเรยนตองเรยนพนธศาสตร มนมประโยชนอยางไรคะ
Tanya:: มประโยชนยงไงเหรอคะ เออ หนมองวา พนธศาสตรเนย มนเปนวชา คอ เราศกษาเกยวกบพนธกรรม แลวกพวกสารพนธกรรมในรางกาย ทวาถายทอดไปสรนลกหลานใชมยคะ เพราะฉะนนหนวามนนาจะ
สามารถบอกได มนทาใหเราเคาเรยกวาไงอะไขขอของใจเกยวกบเรอง
ของโรคทตดมาทางพนธกรรม หนมองในประเดนนนเพราะวาอยางของ
หนเปนโรคโลหตจาง เปนไทรอยดแบบเนย กคอตอนแรก หนกสงสย
วา เออ พอกบแมหนกไมไดเปน หนกด พอมาดสาย ออ ตาหนเปน แลวเหมอนกแบบแมหนเปน gene แฝง พอหนเปน gene แฝง มา
หนกเลยเปนคะ โลหตจางกไอตาแหนงของตวโปรตนมนเปลยนไป ตว
ท 6 โครงสรางเรากไมเหมอนคนอน มนกทาใหเราแบบเราเขาใจมาก
ขน วาทเราเปนอาการแบบน หรอมลกษณะแบบน เกดขนเนยเปนเพราะ
อะไร
Summary. In the literature review, I argued that, as a result of the current content
organization and instructional strategies, most high school students either lack an understanding
of the two models or conceptualize multiple models separately even after the instruction.
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Significantly, a majority of students in this study developed meaningful connections between
models. Connections, both partial and complete, between multiple models of the gene are
necessary for a coherent understanding of genetics. The results indicate that the designed
learning materials effectively promoted students’ coherent understanding of genetics by bridging
the core idea of genetics: the gene concept. The designed materials challenge students to think
about how to connect two models, and they provide problems requiring both models to solve,
rather than simply describing the correct connection. Moreover, some students interchangeably
applied the multiple models to explain genetic phenomena, especially the students in the
integration group. The interchangeable use of representations is a sign of expertise in a domain.
Students could apply their knowledge in reasoning about genetic phenomena. The results
indicated that students developed an integrated knowledge about the gene when they were
required to make explicit connections and when the models were integrated in the context of a
problem.
Cross-case analysis between default model and application.
This cross-case analysis unpacks a relationship between students’ default ideas about the
gene and the levels of connections between multiple models (see Figure 17). The left side of the
figure represents the students in a classical model group, and the right side represents the
students in a molecular model group. The Y axis refers to the level of connections between the
models, from separation to integration that the students constructed during the interviews. The
numbers in the circle represents the coded types of teaching approaches teachers used to
implement the tools.
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Figure 17. Cross-Case Analysis of Students’ Conceptions of Multiple Models of the Gene.
Note. The white circle represents a student from the intervention group, and the black circle
represents a student from the control group. The number in each circle represents the coded
teaching approach. The number 1 indicates the incorporation of the tools in the lesson plan; the
number 2 indicates the use of the tools as extra activities; and the number 3 indicates the use of
the tools as assessment.
Firstly, a diagram illustrates the pattern of the relationship between students’ default
models and the level of connections. Based on the interviews, a majority of students held the
classical model as default model, instead of the molecular model. On the right side, the results
reveal that the students who held the molecular model as the default model were likely to
illustrate better connections between the classical model and the molecular model, similar to the
teacher results. Most of the students in the molecular group were coded into the integration level.
On the other hand, the data of the students who held the classical model as the default model (on
3 2 2
1 1
3
2 3
2
1 2
Inte
grat
ion
Part
ial
Con
nect
ion
Sepa
ratio
n O
ne M
odel
SRC07 SRM04
SRC09 SBP16 SBD14
SBS10 SRM03
SBP17 SBD15
SBV21 SBP18 SRC08
Classical Model Molecular Model
2
1
1 1
1 1 2
SRM01
SBS11 SBS12 SBD13
SBV19 SBV20 SRC06 SRM05 SRM02
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the left side) were equally scattered across the graph, ranging from one model level to integration
level. The analysis confirmed that those with the molecular default model construct more explicit
connections than those with the classical default model. The results showed that half of the
default classical model group was ranked in one model category and separation category.
Another half of the classical model group could construct either partial connection or integration
between multiple models. This contrasts with the teacher results in which teachers with the
classical default model did not show any model connections in their explanations.
In the control group, most students still lacked background knowledge regarding the
molecular model. Although the SBV21 student illustrated her understanding of the molecular
model, unlike most students form the intervention group, she could not elaborate connections
between multiple models.
This analysis is particularly important because it highlights that the designed learning
materials are productive in helping students link unconnected information on the gene concept
presented in the current textbook. Engaging in multiple linked representations of the gene
positively increased the level of connection between the two models for both groups of
students—the classical and molecular model groups. One unexpected, yet promising, result is
that with the designed learning materials several students with the classical default model also
developed integrated knowledge of the gene concept. The initial hypothesis in my master’s thesis
was that, in order to construct a complete connection, students need to conceptualize the
molecular gene as the primary model. Regardless of a default model, the materials empowered
explicit and meaningful interconnections between the models in students’ mind.
Secondly, the cross-case analysis uncovered the relationship between the teaching
approach teacher participants used to implement the tools and students’ levels of model
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connection. The students from the same school were mostly grouped in the same tier. This could
be due to the effect of teaching strategies and time spent by the teacher participants on the
designed learning materials in the classrooms. For example, the teachers in the group 1 teaching
approach, Pakorn and Kanika, integrated the designed learning materials into their lessons and
guided their students through the activities, rather than using the materials for homework
assignments. The students from their classrooms were mostly coded at the integration level. On
the other hand, Wanida used the materials for homework assignments, yet none of the students
demonstrated an integrated understanding. Other extraneous variables that could also influence
the students’ results include student background knowledge and prior preparation in science. For
example, compared to the schools in Rawai city, the schools in Banchang city were considered
more prestigious, where more students demonstrated higher achievement in science.
Moreover, I examined students’ understanding of the proteins to explore their
understanding of the relationships among genes, proteins, and traits. Table 16 shows a summary
of codes across student cases. The students’ responses were coded based on their levels of
scientific explanation about the protein in the interviews. The analysis showed that the students
demonstrating higher level of connection showed better understanding of the function and the
structure of proteins. In addition, the students who made higher levels of connections provided
scientific explanations containing more concrete relationships among genes, proteins, and traits.
In contrast, the students who made lower levels of connections mostly did not provide complete
explanation of underlying processes from genes, proteins, to phenotypes. The connection
between models of the gene concept is necessary for the ability to reason across genetics
domains and across different biological levels.
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Table 16
A Summary of Students’ Conceptions and Connections of Multiple Models of the Gene across Cases
Questions using multiple models
School Student Default Model
Drawing of the gene
General questions on genetic traits
1 linking two representations
2 explaining gene expression of flower colors
Coded connection (1 and 2)
Knowledge on proteins
San garden Niran C C M IG IG IG High Chakrit M Multi M IG IG IG High Jate M Multi M IG IG IG High
Rawai
Tanya M M C IG SP IG High Davis C C C SP IG IG Average Ratana C C C SP SP SP Average Ananda C C C SP SP SP Low Bonmee C C C SP SP SP Low
Montapa
Sittichok C C C SP IG IG High Anna C C M SP PC PC High Pornlaka C C C SP SP SP Low Nawapon C M C SP SP SP Low
Deep holy Ritda M Multi M IG IG IG High Maha M Multi C PC PC PC High Piya C Multi C PC PC PC Average
Park river Somchai C C C PC PC PC Low Vit C C C PC SP PC Average Kawin C C C SP SP SP Low
Victory Wally C C C SP SP SP Low Yot C C C SP SP SP Low Panee M C C SP SP SP Average
Note. ‘C’ represents the classical model. ‘M’ represents the molecular model. ‘Multi’ represents multiple representations of the gene. ‘SP’ represents separation between the models. ‘PC’ represents partial connection between the models. ‘IG’ represents integration between the models.
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CHAPTER 6: Discussions and Conclusions
This research study was motivated by a practical problem in the classroom: students have
difficulty understanding molecular genetics, and because multiple models of the gene were
taught without theoretical consistency and explicit connections, students have often trouble
interpreting and connecting these multiple models of the gene and apply them appropriately.
Hence, in the interest of teaching and learning these different gene models, this design-based
research sought to explore effective teaching pedagogies for developing integrated knowledge
and meaningful application of multiple models. In this concluding chapter, I will discuss the key
findings and their implications for classroom instruction and science education. The research
questions addressed were:
1. What are teachers’ content knowledge and pedagogical content knowledge about the
multiple models of the gene?
2. What are effective pedagogical strategies for teaching multiple models of the gene
with the goal of coherent, integrated, and meaningful understanding?
3. How do the learning materials created in this design-based research project impact
student understanding of multiple models of the gene?
4. What are the factors that influence the implementation of the designed learning
materials in Thai classrooms?
Key Findings
Genetics is explained through the use of multiple models of the gene, where model is
defined as a representational and reasoning system to explore, explain, and predict scientific
phenomena (Frederiksen & White, 2002). In the study of genetics, a gene model is often used as
a tool for scientists and students to understand and solve complicated problems. Different forms
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of models are used to capture different aspects of complex phenomena, serve different purposes
to answer a set of questions, and are constructed within different explanatory discourses (Waters,
2008). A model is made visible by a representation. Because no one single visual explanation of
the gene could convey all of its relevant properties, multiple representations are required to
depict each gene model (Coll & Lajium, 2011).
In genetics, two distinct models of the gene are used to solve genetic problems. First, the
classical model depicts the gene as a particle and is used for explaining questions about genetic
inheritance. Second, the molecular model depicts the gene as a sequence of instruction and is
used for explaining gene expression and genetic inheritance at the molecular level. In
contemporary scientific practice, scientists coordinate both models to investigate gene function
and relevant processes in complex biological phenomena (Portin, 2002). As cultural artifacts,
these models are disseminated and can be found in high school curriculum and in classrooms
(Gericke & Hagberg, 2010).
The analysis in Chapter 2 showed that current high school genetics curricula had
typically presented multiple models separately as classical and molecular units without providing
any explicit connections between the two models. This has resulted in conceptual difficulties in
learning genetics across domains. When students encounter nonintegrated multiple models, they
struggle to develop an understanding of the molecular model and an understanding of the
underlying biological processes (Auckaraaree, 2009; Duncan & Reiser, 2007; Tsui & Treagust,
2007; Venville, Gribble, & Donovan, 2005; Venville & Treagust, 1998).
To alleviate this issue, learners must learn to coherently construct conceptual linkages
between the classical and molecular models in order to alleviate this impediment. Research had
demonstrated that learners often construct and utilize their knowledge best when their ideas are
193
connected (NRC, 2005). This connection is therefore important for students in applying both
models appropriately and for explaining phenomena meaningfully across the boundaries of
genetic domains.
Understanding of the gene. This section discusses how student and teacher participants
understood the gene concept, and how they applied multiple models to explain genetics
phenomena. This exploration is a foundation for formulating a learning theory based on students’
conceptual linkages (or lack thereof) between multiple models.
First, the results showed that the teachers and students conceptualized the gene in many
ways and these conceptions aligned with the classical or the molecular models of the gene. The
way participants explained a particular gene model was usually informed by a combination of
conceptual representation of the model and its functions. For instance, teachers who used the
molecular model conceptualized the gene as the sequence of instruction in relation to the next
steps in transcription and translation processes. The participants then described the definition of a
gene and drew a picture—a coded model is considered as a default model. Regarding individual
preferences of models, most teachers selected the default molecular model, while most students
opted for the default classical model. The analysis of default models help scaffold teacher and
student knowledge structure: (a) the salient model is significantly dominant in their scientific
discourse about genetic phenomena—possibly in their teaching for the teacher cases; and (b) the
participants with the default molecular model remarkably developed higher levels of connections
between the models. Although both models are significant for building the connection, having
the default molecular model could indicate that the participants had a better understanding of the
molecular model and were prompt to talk about connections.
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The second question of how the participants applied multiple models to explain genetics
phenomena helped us understand how the two models can be coherently integrated, leading to
ideas in developing more effective pedagogical tools. Most participants showed an understanding
of both models in their explanations of genetic phenomena. The results revealed that, without
leading questions about connections, most participants—including both students and teachers—
usually applied the two models in separation to a particular domain. As mentioned above, such a
strict distinction between the two models mirrors how the gene concept was currently presented
and taught in the curricula. Models can be used separately to solve particular questions in
domains of application; however participants who did not understand the connection between the
two models usually relied only on their default model alone. While this level of understanding is
applicable to solve questions found in high school exams that are neatly situated within one
domain, both models are required to solve authentic problems or provide meaningful scientific
explanations for underlying processes. As evidence showed in this study, the participants who
possess adequate knowledge of both models but did not perceive the connections often had
difficulties with problems that required them to reason based on knowledge of both models.
Another way that participants applied multiple gene models was through partial
connection. Most teachers and some students demonstrated partial connections after they
encountered questions that required understanding of multiple models. This partial connection
involved mapping visual representations of the gene from the classical model (a section on
chromosome representation) to the molecular model (a DNA molecule representation). This
partial connection between multiple visual representations is commonly found in textbooks used
for teaching the biological structures of genetic materials. Despite their understanding of
connections across different visual representations, participants did not demonstrate bridges
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across symbolic representations of the classical model (allele representation) and the molecular
model (DNA sequence representation). The linkage between those symbolic representations is
important for deploying these models as tools because symbolic representations play an essential
role in allowing scientists and learners to explore and predict genetic problems. For instance,
scientists can compare nucleotide sequences from different species and use this symbolic
representation of the molecular model to predict the evolution of the organisms. Without the
connections between different symbolic representations, their reasoning will not be complete; in
other words, they solved problems without addressing functions of models and contexts of
phenomena.
The results from both separation and partial connection suggest that it is difficult to build
linkages between the models, even for individuals who already have adequate knowledge of both
models. Because many participants were unable to establish connections between the two gene
models, they were not able to reason and solve problems across both the classical and molecular
domains.
At the same time, this study also revealed promising evidence of conceptual linkages
between the classical and molecular models when certain participants applied both models in
integration. The results showed that prior to the workshop, some teachers demonstrated fully
integrated connections between multiple models of the gene. After the intervention, most
students showed an integrated knowledge associated with both models of the gene concept. They
answered questions using explanations that drew on both the classical and molecular models.
Four emergent properties for model integration are identified: a) the classical and molecular
models were applied concurrently in a single explanation; b) explicit connections of biological
structures between the two models were constructed; c) the functions of both models were used
196
complementarily with each other to explain a genetic phenomenon; and d) both models were
situated in a rich genetic context. For example, the teacher, Pakorn, applied both models to
explain what causes the differences between black phenotype and white phenotype, which
demonstrated that he could apply models in a genetic context. Using both models
complementarily, his explanation included functions of the gene on genetic inheritance and gene
expression.
The questions of what knowledge is necessary to mediate between the two models and
makes it possible to apply both of them are complex. As a basis for model integration, learners
need to possess: a) a conceptual understanding of both classical and molecular models in
explaining questions in its domains—in particular, the functions of both models; and b) an
understanding of the connections between genetic materials represented with different biological
scales, which is demonstrated as making partial connections. Here, I further argue that the ability
to construct conceptual linkages between models at the integration level is not simply a
combination of one’s knowledge of the two models. As shown in the partial connection group,
they understood connections between the two models, but they lacked knowledge of how both
models complemented each other and functioned together in explaining authentic genetic
problems. Full integration requires learners to be capable to apply the two models
complementarily in solving problems, instead of merely constructing conceptual linkages in their
minds. This is important to scientific research and teaching because synthesis between functions
of the classical and molecular models will lead to clearer and more meaningful scientific
explanation. By being able to select different gene models and switching their applications in
relation to particular problems, individuals will be more capable in solving complex gene
phenomena.
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Curriculum and Pedagogies. During the study, the existing genetic curricula
incoherently presented multiple models of the gene. The result was that students developed a
fragmented knowledge of the gene after finishing the genetics unit. This study confirmed that the
teachers taught the gene concepts without providing explicit connections between the models.
Previous research had shown that even experienced teachers with a sound knowledge of models
could have difficulties in teaching those same models (Buty and Mortimenr, 2008). In this study,
the teachers were not aware of the role of multiple models of the gene in high school genetics,
and how they influenced students’ understanding and applications of them. Through the research
process, the teachers themselves developed a more integrated understanding of genetics and
learned how to teach genetics in a new way. Prior to the study, their pedagogical content
knowledge on how to enhance students’ integrated knowledge of models was at an early stage.
This design-based research project drew from learning theories and teachers’ existing knowledge
to create learning materials connected the multiple gene models.
Importantly, the results indicate that the designed learning materials effectively promoted
students’ coherent understanding of genetics—in other words, students were able to develop an
integrated understanding of the gene models using these new materials. In addition, students also
developed knowledge about the structure and function of proteins: their explanations
demonstrated that they understood the relationship among genes, proteins, and phenotypes. The
designed materials challenged students to engage in learning activities with multiple linked
representations to construct explicit connections and to apply integrated models to solve genetics
problems. The proposed pedagogical strategies for systematic teaching of multiple models
involved: a) engaging students in multiple representations concurrently and in constructing
explicit connections; b) offering genetic situations/contexts for students to acquire the new
198
knowledge structures of integrated models; and c) connecting ideas about genes, proteins, and
phenotypes in the circle of representations in genetics (see Figure 18).
While students already deploy multiple representations of the gene in high school
genetics, these different representations become even more powerful and productive when they
are linked to each other; this way, students can better understand the connections between the
various types of representations of a phenomenon and integrate the ideas depicted in those
representations (Kozma, 2000). By connecting the different representations and actively
constructing more coherent ideas, learners can also benefit from the complementary functions of
multiple representations (Ainsworth, 2006). The manipulation of multiple linked representations
supports the two existing models to explain the same phenomena, bring synergistic effects to the
construction of coherent knowledge structures (Treagust & Tsui, 2013). In learning with multiple
linked representations, students engaged in visually interpreting and constructing linkages
between multiple representations visually, so they could intellectually integrate their mental
models of the gene (Frederiksen & White, 2002).
When knowledge from different models must be combined to solve a problem,
connections must be made: in other words, the concepts from one representation must be mapped
onto the concepts from other related representations in order to perform the task using both sets
of knowledge (Gilbert et al., 2008). Boshuizen and Schmidt (1992) pointed out that real
situations are the primary source of information in which linkages among multiple
representations are useful or important. Lesgold (1998) proposed that contexts are the basis for
acquiring new knowledge structures and forming new links among the knowledge learners
already have. Therefore, it is important to design learning materials that are embedded in
authentic situations based on reasoning across genetic domains. In such situations, students are
199
required to reasoning with integrated models to simultaneously describe genetic inheritance and
gene expression to phenotypes. Indeed, this study found that using multiple models in solving
contextual problems helped students improve their strategic knowledge: knowing when and how
to apply the models.
Figure 18. The cycle of representations in genetics
All things considered, I contend that curriculum and pedagogies for high school genetics
should be designed to complete a cycle of representations for a more coherent, integrated, and
meaningful understanding of genetics. To merge knowledge across genetics units, as is necessary
for explaining authentic genetic problems, all representations of concepts in the cycle must be
linked continuously. In classical genetics unit, we begin the lesson with alleles to chromosomes
to DNA molecules. In molecular genetic unit, we begin the lesson with DNA molecular to
DNA molecule
Nucleotide sequence Chromosome
Phenotype
Amino acid sequence
Protein
Gene Expression
Genetic Inheritance
Allele
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sequences to amino acid sequences and to proteins. As demonstrated, linking multiple
representations of the gene will lead to a more integrated knowledge of multiple models of the
gene, and to the development of necessary cognitive tools for explaining genetic phenomena. In
addition, instruction also needs to address the role of proteins because they are the products of
the gene that control phenotypes. Lastly, instruction needs to bridge all elements to interesting
phenotypes that foster fruitful understanding by linking representations to the real world. The
ultimate pedagogical goal is for the learner to acquire his/her own strategies for connecting
multiple representations and conceptually integrate both models to solve problems.
Limitations of the Study
This section discusses limitations that could potentially impact the study’s ability to
effectively answer the research questions. Firstly, I did not collect the type of data that would be
used under ideal conditions to examine the effectiveness of these tools. For instance, I did not
collect pre-intervention data with the same students or post-intervention data with the same
teachers. Although the results of non-intervention data from my master’s thesis and the control
group were remarkably comparable to the results of intervention data, the samples were different
in terms of time and place. The small size of the control group also limited my ability to establish
data patterns in regards to students’ learning. To justify this limitation, the analysis was drawn
from both sources and was able to contribute to a constructive pattern of non-intervention results.
Second, the differences in teacher participants and school contexts could influence the
results of students’ learning in genetics, in addition to the effects of the designed tools. For
example, the students from prestigious schools in Banchang city could have considerably
stronger background knowledge, so they were likely to perform better than the students from
schools in Rawai city. The complexity of multiple variables was expected in this research design,
201
but using a variety of classroom contexts allowed me to appropriately contextualize and
generalize the results. In the analysis, I attempted to address some variables such as the
differences in teachers’ pedagogical approach.
Finally, the teaching practices of some teachers did not change from the traditional
lecture approach at all after participating in the workshop, which could result in limited ability of
this study to fully incorporate the tools in some cases. Although it was not the purpose of the
study to control teachers’ instructional use of the tools, this limited usage could affect students’
learning outcomes. In addition, the workshops also were not designed to dramatically change
their teaching practice or beliefs about science teaching, since such reform requires sustained
professional development. With an attempt to leverage teacher commitment, in the workshop
teachers discussed and scaffold students’ learning in relation to their practice.
Implications for Practice and Research
This study bridges a gap between educational research and practice by situating research
in the authentic context of instruction and introducing educational research about students’
understanding of genetics into classroom practice. The practical value of this research is that the
designed pedagogical tools developed for this study could be implemented in genetics classroom
as learning activities promote a more comprehensive understanding of genetics. The results of
this study revealed specific factors mediating the construction of linked models, which is helpful
for designing more effective pedagogical tools and curricula in the future. Finally, the finding
that the genetics must be taught as an integrated and interconnected concept is immensely
important to revising the existing curricula and textbooks that are commonly used. In addition to
the development in biology curriculum, findings from this research also contribute to the work
on professional development for biology teachers. The pedagogical tools allow teachers to help
202
students in developing a more comprehensive and integrated concept of the gene, and may also
help them critically examine their own pedagogical approaches. The study also pointed out the
need for professional development to leverage teachers’ integrated knowledge of genetics and to
improve their pedagogical approaches. For example, teachers should have awareness of the
existence of multiple models in curriculum and student challenges in learning from current
teaching approach.
In addition to pedagogical implications, this study also contributes to existing literature
on this topic by beginning s to fill the research gaps on the teaching and learning genetics.
Specifically, my study investigated knowledge structure and instructional approaches that rely on
a complementary view of gene models in the classical and molecular genetics domains. While
previous research has focused mainly on classical genetics, the current research has shifted to
promoting molecular genetics. As Redfield (2012) contended, “the brief time high school and
first-year university students devote to genetics shouldn’t be wasted on Mendel’s laws and
Punnett squares” (p.4) students should instead learn to solve problems related to molecular
genetics. With this direction, genetics knowledge would be treated repeatedly as disconnected
concepts that eventually hinder students’ learning and understanding. The results of my study
suggested that gene models should be viewed as complementary to each other instead for solving
genetic phenomena. The study, therefore, offers a useful framework of multiple linked models to
promote synergistic and meaningful understanding of both domains that can be used by the
educational research community to examine other questions related to genetic education.
Moreover, this study also supports the use of model-based learning as a key for research
and practice in science education. The findings from this study, therefore, could improve our
understanding of teacher and student knowledge structures in other science topics such as energy
203
and chemical particles, in which multiple models are deployed. This study could also expand
current research on multiple representations, which has only examined the role of multiple
representations in relation to bridging different modes of representations. Utilizing this
framework, educators will then be able to design learning materials for integration across
scientific models.
Future studies should continue to advance the design process by examining in greater
detail what the connections between different models look like and under what conditions they
are made. For example, the pedagogical approach needs to be infused throughout the teaching
processes in the genetics curriculum, and the multiple linked representations need to be
embedded in contextualized genetics problems. In addition, future studies could take situative
learning theory to investigate the interaction between learning with scientific models and
social/cultural factors. Since, scientific models are tools that socially constructed and learning
how to use models involves situating them across situations.
Moreover, a systematic analysis of the interaction between teachers’ practice and the
ways students engage with multiple models over the genetic course could also advance the
design. We also need better evidence on how to help teachers incorporate the proposed
pedagogical tools in their classrooms and to challenge them to analyze their current practices. As
shown in this study, teaching multiple models in integration is not an easy task for teachers;
teachers need professional development encompassing both knowledge and pedagogical content
knowledge regarding the integration of multiple models. The results of this study offer a baseline
for future studies in these areas.
204
References
American Association for the Advancement of Science. (1993). Benchmarks for Science Literacy (Vol. 1993, p. 448). New York, NY: Oxford University Press.
Abell, S., & Lederman, N. (2007). Research on science teacher knowledge. In Handbook of research on science education (pp. 1105–1149). New York, NY: Routledge.
Ainsworth, S. (1999). The functions of multiple representations. Computers & Education, 33(2-3), 131–152. doi:10.1016/S0360-1315(99)00029-9
Ainsworth, S. (2006). DeFT: A conceptual framework for considering learning with multiple representations. Learning and Instruction, 16(3), 183–198. Retrieved from http://www.sciencedirect.com/science/article/pii/S0959475206000259
Albuquerque, P. (2008). Gene concepts in higher education cell and molecular biology textbooks. Science Education International, 19(2), 219–234.
Anderson, J. R., Greeno, J. G., Reder, L. M., & Simon, H. A. (2000). Perspectives on Learning, Thinking, and Activity. Educational Researcher, 29(4), 11–13. doi:10.3102/0013189X029004011
Auckaraaree, N. (2009). An Exploration of Thai High School Students’ Understanding of Molecular Genetics and Gene Expression. (Unpublished master's thesis).University of Wisconsin, Madison, Wisconsin.
Banet, E., & Ayuso, G. E. (2003). Teaching of biological inheritance and evolution of living beings in secondary school. International Journal of Science Education, 25(3), 373–407. doi:10.1080/09500690210145716
Bassok, M., & Holyoak, K. (1989). Interdomain transfer between isomorphic topics in algebra and physics. Journal of Experimental Psychology: Learning, Memory, and Cognition, 15(1), 153–166. doi:10.1037/0278-7393.15.1.153
Beach, K. (1995). Activity as a mediator of sociocultural change and individual development: The case of school‐work transition in Nepal. Mind, Culture, and Activity, 2(4), 285–302. doi:10.1080/10749039509524707
Brown, A. L. (1992). Design Experiments: Theoretical and Methodological Challenges in Creating Complex Interventions in Classroom Settings. Journal of the Learning Sciences, 2(2), 141–178. doi:10.1207/s15327809jls0202_2
Brown, A. L., & Campione, J. C. (1994). Guided discovery in a community of learners. In Class lessons: Integrating cognitive theory and classroom practice (pp. 229–270). Cambridge, MA: MIT Press.
205
Brown, J., Collins, A., & Duguid, P. (1989). Situated cognition and the culture of learning. Educational Researcher, 18(1), 32–42. doi:10.1037/0003-066X.53.1.5
Bruner, J. S. (1960). The Process of Education. Cambridge, MA: Harvard University Press.
Cartier, J. (1999). Using a modeling approach to explore scientific epistemology with high school biology students (Res. Rep. 99-1). Madison, WI: National Center for Improving Student Learning and Achievement in Mathematics and Science. (Available at http://www.wcer.wisc.edu/ncisla/).
Cartier, J., Rudolph, J., & Stewart, J. (2001). The nature and structure of scientific models. Madison, WI: The National Center for Improving Student. Learning and Achievement in Mathematics and Science.
Cartier, J., & Stewart, J. (2000). Teaching the nature of inquiry: Further developments in a high school genetics curriculum. Science & Education, 9, 247–267. doi:DOI 10.1007/s10734-004-9448-9
Chi, M. (1992). Conceptual change within and across ontological categories: Examples from learning and discovery in science. Cognitive Models of Science Minnesota Studies in the Philosophy of Science, 15, 129–160.
Chi, M. (2008). Three types of conceptual change: Belief revision, mental model transformation, and categorical shift. In S. Vosniadou (Ed.), Handbook of research on conceptual change (pp. 61–82). Hillsdale, NJ: Erlbaum.
Clermont, C. P., Borko, H., & Krajcik, J. S. (1994). Comparative study of the pedagogical content knowledge of experienced and novice chemical demonstrators. Journal of Research in Science Teaching, 31(4), 419–441. doi:10.1002/tea.3660310409
Clermont, C. P., Krajcik, J. S., & Borko, H. (1993). The influence of an intensive in-service workshop on pedagogical content knowledge growth among novice chemical demonstrators. Journal of Research in Science Teaching, 30(1), 21–43. doi:10.1002/tea.3660300104
Cobb, P. (2001). Supporting the improvement of learning and teaching in social and institutional context. In S. Carver & D. Klahr (Eds.), Cognition and instruction: Twenty-five years of … (pp. 455–478). Cambridge, MA: Lawrence Erlbaum Associates.
Cobb, P., Confrey, J., DiSessa, A., Lehrer, R., & Schauble, L. (2003). Design Experiments in Educational Research. Educational Researcher, 32(1), 9–13. doi:10.3102/0013189X032001009
Cobern, W. W. (1996). Worldview theory and conceptual change in science education. Science Education, 80(5), 579–610. doi:10.1002/(SICI)1098-237X(199609)80:5<579::AID-SCE5>3.0.CO;2-8
206
Coll, R. K., & Lajium, D. (2011). Modeling and the Future of Science Learning. In M. S. Khine & I. M. Saleh (Eds.), Models and Modeling: Cognitive tools for scientific enquiry (pp. 1–21). London: Springer.
Collins, A, Greeno, J., & Resnick, L. (1996). Cognition and learning. In B. Berliner & R. Calfee (Eds.), Handbook of Educational Psychology (pp. 15–46). New York, NY: MacMillan.
Collins, Allan. (1992). Toward a design science of education. In E. Scanlon & T. O’Shea (Eds.), Proceedings of the NATO advanced research workshop on new directions in advanced educational technology (pp. 15–22). Berlin, Heidelberg: Springer. doi:10.1007/978-3-642-77750-9
Collins, Allan, Joseph, D., & Bielaczyc, K. (2004). Design Research: Theoretical and Methodological Issues. Journal of the Learning Sciences, 13(1), 15–42. doi:10.1207/s15327809jls1301_2
Condit, C. M. (1999). How the public understands genetics: non-deterministic and non-discriminatory interpretations of the “blueprint” metaphor. Public Understanding of Science, 77(1), 1–9.
Condit, C. M. (2010a). Public understandings of genetics and health. Clinical Genetics, 77(1), 1–9.
Condit, C. M. (2010b). Public attitudes and beliefs about genetics. Annual Review of Genomics and Human Genetics, 11(May), 339–359.
Crawford, K. (1996). Vygotskian approaches in human development in the information era. Educational Studies in Mathematics, 31(1-2), 43–62. doi:10.1007/BF00143926
Creswell, J. W. (2012). Educational Research: Planning, Conducting, and Evaluating Quantitative and Qualitative Research (4th ed., p. 672). Boston, MA: Pearson College Division.
Dawson, V., & Venville, G. (2011). Argumentation strategies used by teachers to promote argumentation skills about a genetics socioscientific issue. In ERIDOB 2010.
De Jong, T., Ainsworth, S., Dobson, M., van der Hulst, A., Levonen, J., Reimann, P., … Swaak, J. (1997). Acquiring Knoweldge in Science and Mathematics: The Use of Multiple Represetations in Technology-Based Learning Enviroments. In M. van Someren, P. Reimann, H. Boshuizen, & T. de Jong (Eds.), Learning with multiple represetations. Kidlington, Oxford: Elsevier Science.
De Jong, T., & Ferguson-Hessler, M. G. M. (1991). Knowledge of problem situations in physics: A comparison of good and poor novice problem solvers. Learning and Instruction, 1(4), 289–302. Retrieved from http://www.sciencedirect.com/science/article/pii/0959475291900106
207
De Jong, O. Van Driel, J. (2005). Exploring the Development of Student Teachers? PCK of the Multiple Meanings of Chemistry Topics. International Journal of Science and Mathematics Education, 2(4), 477–491. doi:10.1007/s10763-004-4197-x
Dechsri, P., Eamsukkawat, S., & Ketwadee, K. (2008). Thialand. In G. M. Mullis, I.V.S., Martin, M.O., Olson, J.F., Berger, D.R., Milne, D., & Stanco (Ed.), TIMSS 2007 Encyclopedia: A Guide to Mathematics and Science Education Around the World, Vol. 2. Chestnut Hill, MA: TIMSS & PIRLS International Study Center, Boston College.
DiSessa, A. A. (1982). Unlearning Aristotelian physics: a study of knowledge-based learning. Cognitive Science, 6(1), 37–75. Retrieved from http://www.sciencedirect.com/science/article/pii/S0364021382800050
diSessa, A. A. (2004). Metarepresentation: Native Competence and Targets for Instruction. Cognition and Instruction, 22(3), 293–331. Retrieved from http://eric.ed.gov/?id=EJ682746
Driver, R., Asoko, H., Leach, J., Scott, P., & Mortimer, E. (1994). Constructing Scientific Knowledge in the Classroom. Educational Researcher, 23(7), 5–12. doi:10.3102/0013189X023007005
Duit, R., & Treagust, D. F. (2003). Conceptual change: a powerful framework for improving science teaching and learning. International Journal of Science Education, 25(6), 671–688. doi:10.1080/0950069032000076652
Duncan, R. G. (2007). The Role of Domain-Specific Knowledge in Generative Reasoning About Complicated Multileveled Phenomena. Cognition and Instruction, 25(4), 271–336. doi:10.1080/07370000701632355
Duncan, R. G., & Reiser, B. J. (2007). Reasoning Across Ontologically Distinct Levels : Students ’ Understandings of Molecular Genetics. Journal of Research in Science Teaching, 44(7), 938–959. doi:10.1002/tea
Duncan, R. G., & Tseng, K. A. (2011). Designing project-based instruction to foster generative and mechanistic understandings in genetics. Science Education, 95(1), 21–56. doi:10.1002/sce.20407
Falk, R. (2000). The gene–A concept in tension. In R. F. P. J. Burton & & H.-J. Rheinberger (Eds.), The concept of the gene in development and evolution: Historical and epistemological perspectives (pp. 317–348). New York, NY: Cambridge University Press.
Finley, F. N., Stewart, J., & Yarroch, W. L. (1982). Teachers’ perceptions of important and difficult science content. Science Education, 66(4), 531–538. doi:10.1002/sce.3730660404
Flodin, V. S. (2009). The Necessity of Making Visible Concepts with Multiple Meanings in Science Education: The Use of the Gene Concept in a Biology Textbook. Science & Education, 18(1), 73–94. doi:10.1007/s11191-007-9127-1
208
Francoeur, E. (1997). The Forgotten Tool: The Design and Use of Molecular Models. Social Studies of Science, 27(1), 7–40. doi:10.1177/030631297027001002
Franke, G., & Bogner, F. X. (2011). Conceptual Change in Students’ Molecular Biology Education: Tilting at Windmills? The Journal of Educational Research, 104(1), 7–18. doi:10.1080/00220670903431165
Frederiksen, J., & White, B. (2002). Conceptualizing and connstructing linked models: Creating coherence in complex knowledge systems. In A. T. P. Brna, M. Baker, K. Stenning (Ed.), The Role of Communication in Learning to Model (pp. 69–96). NJ: Erlbaum.: Mahwah.
Freidenreich, H. B., Duncan, R. G., & Shea, N. (2011). Exploring Middle School Students’ Understanding of Three Conceptual Models in Genetics. International Journal of Science Education, 33(17), 1–27. doi:10.1080/09500693.2010.536997
Friedrichsen, P. M., & Stone, B. (2004). Examining students’ conception of Molecular Genetics in an Introductory Biology course for non-science majors: A self study. In Paper presented at the National Association for Research in Science Teaching International Conference. Vancouver, WA.
Gericke, N. M., & Hagberg, M. (2006). Definition of historical models of gene function and their relation to students’ understanding of genetics. Science & Education, 16(7-8), 849–881. doi:10.1007/s11191-006-9064-4
Gericke, N. M., & Hagberg, M. (2009). Conceptual Incoherence as a Result of the use of Multiple Historical Models in School Textbooks. Research in Science Education, 40(4), 605–623. doi:10.1007/s11165-009-9136-y
Gericke, N. M., & Hagberg, M. (2010). Conceptual Variation in the Depiction of Gene Function in Upper Secondary School Textbooks. Science & Education, 19(10), 963–994. doi:10.1007/s11191-010-9262-y
Gess-Newsome, J., & Lederman, N. G. (1993). Preservice biology teachers’ knowledge structures as a function of professional teacher education: A year-long assessment. Science Education, 77(1), 25–45. doi:10.1002/sce.3730770103
Gess-Newsome, J., & Lederman, N. G. (1995). Biology teachers’ perceptions of subject matter structure and its relationship to classroom practice. Journal of Research in Science Teaching, 32(3), 301–325. doi:10.1002/tea.3660320309
Giere, R., Bickle, J., & Mauldin, R. (1991). Understanding scientific reasoning (3rd ed.). Forth Worth, TX: Holt, Rinehart & Winston.
Gilbert, J. K. (Ed.). (2005). Visualization in Science Education (Vol. 1). Dordrech, Netherlands: Springer.
209
Gilbert, J. K., & Boulter, C. (Eds.). (2000). Developing models in science education. Dordrecht, Netherlands: Kluwer Academic Publishers.
Gilbert, J. K., & Osborne, R. J. (1980). “I Understand, but I Don’t Get It”: Some Problems of Learning Science. School Science Review, 61(217), 664–74.
Gilbert, J. K., Reiner, M., & Nakhleh, M. (2008). Visualization: Theory and Practice in Science Education. New York, NY: Springer.
Greene, E. D. (1990). The logic of university students’ misunderstanding of natural selection. Journal of Research in Science Teaching, 27(9), 875–885. doi:10.1002/tea.3660270907
Greeno, J. G., & Hall, R. P. (1996). Practicing Representation. Phi Delta Kappan, 78(5), 361–67.
Groot, A. De. (1965). Thought and choice in chess. The Hague: Mouton Publishers. The Hague: Mouton Publishers.
Grossman, P. (1990). The making of a teacher: Teacher knowledge and teacher education. New York, NY: Teachers College Press.
Halim, L., & Meerah, S. M. M. . (2002). Science Trainee Teachers’ Pedagogical Content Knowledge and its Influence on Physics Teaching. Research in Science & Technological Education, 20(2), 215–225. doi:10.1080/0263514022000030462
Halloun, I. A. (2006). Modeling theory in science education (p. 250). Dordrech, Netherlands: Springer.
Halloun, I. A. (2007). Mediated Modeling in Science Education. Science & Education, 16(7-8), 653–697. doi:10.1007/s11191-006-9004-3
Harrison, A. G., & Treagust, D. F. (1998). Modelling in Science Lessons: Are There Better Ways to Learn With Models? School Science and Mathematics, 98(8), 420–429. doi:10.1111/j.1949-8594.1998.tb17434.x
Harrison, A. G., & Treagust, D. F. (2000). Learning about atoms, molecules, and chemical bonds: A case study of multiple-model use in grade 11 chemistry. Science Education, 84(3), 352–381. doi:10.1002/(SICI)1098-237X(200005)84:3<352::AID-SCE3>3.0.CO;2-J
Hellamy, M. L. (1990). Teacher knowledge, instruction. and student understandings: The relationships evidenced in the teaching of high school Mendelian genetics, unpublished doctoral dissertation,. The University of Maryland, College Park, MD.
Hestenes, D. (1997). Modeling methodology for physics teachers. Proceedings of the International Conference on Undergraduate Physics Education (Vol. 399, pp. 935–957). College Park, MD: AIP. doi:10.1063/1.53196
210
Hestenes, D. (2006). Notes for a modeling theory of science, cognition and instruction. In Modeling in Physics and Physics Education.
Hewson, P. W. (1981). A Conceptual Change Approach to Learning Science. European Journal of Science Education, 3(4), 383–396. doi:10.1080/0140528810304004
Hewson, P. W., & Thorley, N. R. (1989). The conditions of conceptual change in the classroom. International Journal of Science Education, 11(5), 541–553. doi:10.1080/0950069890110506
Hill, H., Ball, D., & Schilling, S. (2008). Unpacking pedagogical content knowledge: Conceptualizing and measuring teachers’ topic-specific knowledge of students. Journal for Research in Mathematics …, 39(4), 372.
Hmelo, C., & Evensen, D. (2000). Problem-based learning: Gaining insights on learning interactions through multiple methods of inquiry. In D. Evensen & C. Hmelo (Eds.), Problem-based learning: A research perspective on learning interactions (pp. 1–18). Mahwah, NJ: Lawrence Erlbaum.
Hull, D. (1974). Philosophy of biological science. Englewood Cliffs, N.J: Prentice-Hall.
Ingham, A. M., & Gilbert, J. K. (1991). The use of analogue models by students of chemistry at higher education level. International Journal of Science Education, 13(2), 193–202. doi:10.1080/0950069910130206
Institue for the Promotion of Teaching Science and Technology. (2001). National science curriculum standards, the basic education curriculum 2544 b.e. Retrieved April 14, 2009, from http://www.ipst.ac.th/math_curriculum/index.html
Institue for the Promotion of Teaching Science and Technology. (2005). Biology volume 5. Bangkok, Thailand: IPST.
Justi, R. S., & Gilbert, J. K. (2002). Modelling, teachers’ views on the nature of modelling, and implications for the education of modellers. International Journal of Science Education, 24(4), 369–387. doi:10.1080/09500690110110142
Kelly, A., Lesh, R., & Baek, J. (2008). Handbook of design research methods in education: Innovations in science, technology, engineering, and mathematics learning and teaching. (Routledge, Ed.). New York, NY.
Kennedy, M. M. (1998). Education reform and subject matter knowledge. Journal of Research in Science Teaching, 35(3), 249–263. doi:10.1002/(SICI)1098-2736(199803)35:3<249::AID-TEA2>3.0.CO;2-R
211
Kind, V. (2009). Pedagogical content knowledge in science education: perspectives and potential for progress. Studies in Science Education, 45(2), 169–204. doi:10.1080/03057260903142285
Kindfield, A. C. H. (1992). Teaching genetics: Recommendations and research. Teaching genetics: Recommendations and research ….
Kindfield, A. C. H. (1994). Biology Diagrams: Tools to Think With. Journal of the Learning Sciences, 3(1), 1–36. doi:10.1207/s15327809jls0301_1
Kitcher, P. (1984). 1953 and all that. A tale of two sciences. The Philosophical Review, 93(3), 335–373.
Kitcher, P. (1999). The hegemony of molecular biology. Biology and Philosophy.
Kitcher, P. (2001). Battling the undead: How (and how not) to resist genetic determinism. In R. S. Singh, C. B. Krimbas, D. B. Paul, & J. Beatty (Eds.), Thinking about evolution: historical, philosophical, and political perspectives (pp. 396–414). New York, NY: Cambridge University Press.
Kozma, R. (2000). The use of multiple representations and the social construction of understanding in chemistry. In M. Jacobson & R. Kozma (Eds.), novations in science and mathematics education: Advanced designs for technologies of learning (pp. 11–46). Mahwah, NJ: Erlbaum.
Kozma, R. (2003). The material features of multiple representations and their cognitive and social affordances for science understanding. Learning and Instruction, 13(2), 205–226. doi:10.1016/S0959-4752(02)00021-X
Kozma, R., & Russell, J. (1997). Multimedia and understanding: Expert and novice responses to different representations of chemical phenomena. Journal of Research in Science Teachingesearch in science teaching, 34(9), 949–968.
Lave, J., & Wenger, E. (1991). Situated learning: Legitimate peripheral participation. New York, NY: Cambridge university press.
Lederman, N. G., Gess-Newsome, J., & Latz, M. S. (1994). The nature and development of preservice science teachers’ conceptions of subject matter and pedagogy. Journal of Research in Science Teaching, 31(2), 129–146. doi:10.1002/tea.3660310205
Lewis, J., & Kattmann, U. (2004). Traits, genes, particles and information: re‐visiting students’ understandings of genetics. International Journal of Science Education, 26(2), 195–206. doi:10.1080/0950069032000072782
212
Lewis, J., Leach, J., & Wood-Robinson, C. (2000). What’s in a cell? — young people's understanding of the genetic relationship between cells, within an individual. Journal of Biological Education, 34(3), 129–132. doi:10.1080/00219266.2000.9655702
Lewis, J., & Wood-Robinson, C. (2000). Genes, chromosomes, cell division and inheritance - do students see any relationship? International Journal of Science Education, 22(2), 177–195. doi:10.1080/095006900289949
Linder, C. J. (1993). A challenge to conceptual change. Science Education, 77(3), 293–300. doi:10.1002/sce.3730770304
Linn, M., Davis, E., & Bell, P. (2004). Internet Environments for Science Education (p. 440). Mahwah, NJ: Lawrence Erlbaum.
Loucks-Horsley, S., Stiles, K. E., Mundry, S., Love, N., & Hewson, P. W. (2009). Designing Professional Development for Teachers of Science and Mathematics (Google eBook) (Vol. 2009, p. 424). SAGE. Retrieved from http://books.google.com/books?hl=en&lr=&id=oXINawcsA0UC&pgis=1
Loughran, J., Berry, A., & Mulhall, P. (2006). Understanding and developing science teachers’ pedagogical content knowledge. Rotterdam, The Netherlands: Sense Publishers.
Loughran, J., Mulhall, P., & Berry, A. (2004). In search of pedagogical content knowledge in science: Developing ways of articulating and documenting professional practice. Journal of Research in Science Teaching, 41(4), 370–391. doi:10.1002/tea.20007
Magnusson, S., Krajcik, J., & Borko, H. (1999). Nature, sources, and development of pedagogical content knowledge for science teaching. In Gess-Newsome & N. G. Lederman (Eds.), Examining pedagogical content … (pp. 95–132). Boston, MA: Springer.
Malacinski, G. M., & Zell, P. W. (1995). Manipulating the “Invisible”: Learning Molecular Biology Using Inexpensive Models. American Biology Teacher, 58(7), 428–32.
Marbach-Ad, G. (2001). Attempting to break the code in student comprehension of genetic concepts. Journal of Biological Education, 35(4), 183–189. doi:10.1080/00219266.2001.9655775
Marbach-Ad, G., Rotbain, Y., & Stavy, R. (2008). Using computer animation and illustration activities to improve high school students’ achievement in molecular genetics. Journal of Research in Science Teaching, 45(3), 273–292. doi:10.1002/tea.20222
Martins, I., & Ogborn, J. (1997). Metaphorical reasoning about genetics. International Journal of Science Education, 19(1), 47–63. doi:10.1080/0950069970190104
213
Martin, M. O., Mullis, I. V. S., & Foy, P. (2008). TIMSS 2007 international science report: Findings from IEA's trends in international mathematics and science study at the fourth and eighth grades TIMSS & PIRLS International Study Center, Boston College.
Mills Shaw, K. R., Van Horne, K., Zhang, H., & Boughman, J. (2008). Essay contest reveals misconceptions of high school students in genetics content. Genetics, 178(3), 1157–68. doi:10.1534/genetics.107.084194
Ministry of Education Thailand. (2012). Educational Statistics. Retrieved from http://www.moe.go.th/English/
Morange, M. (2005). What history tells us. Journal of Biosciences, 30(3), 313–316. doi:10.1007/BF02703668
Moss, L. (2001). Deconstructing the gene and reconstructing molecular developmental systems. In S. Oyama, P. E. Griffiths, & R. D. Gray (Eds.), Cycles of contingency: Developmental systems and evolution (pp. 85–97). Cambridge, MA: The MIT Press.
Moss, L. (2004). What Genes Can’t Do (p. 256). Cambridge, MA: The MIT Press.
Mullis, I.V.S., Martin, M.O., Olson, J.F., Berger, D.R., Milne, D., & Stanco, G.M. (2008). TIMSS 2007 Encyclopedia: A Guide to Mathematics and Science Education Around the World, Volumes 1 and 2
Chestnut Hill, MA: TIMSS & PIRLS International Study Center, Boston College.
Nagel, E. (1961). The structure of science: Problems in the logic of scientific explanation. New York, NY: Harcourt, Brace & World.
Novick, L. R., & Hmelo, C. E. (1994). Transferring symbolic representations across nonisomorphic problems. Journal of Experimental Psychology: Learning, Memory, and Cognition, 20(6), 1296–1321. doi:10.1037/0278-7393.20.6.1296
National Research Council. (1996). National science education standards. Washington, DC: The National Academies Press.
National Research Council. (2005). How Students Learn: Science in the Classroom. Washington, DC: The National Academies Press.
Office of the Basic Education Commission. (2008). The Basic Education Core Curriculum 2008. Retrieved from http://www.obec.go.th/
Office of the Education Council. (2008). Education system, standards, and quality Assurance. In Education in Thailand 2008. Retrieved from http://www.onec.go.th/onec_main/page.php?mod=Category&categoryID=CAT0000463
214
Office of the National Economic and Social Development Board. (2006).The Tenth Nataional Economic and Social Development Plan. Retrieved from http://www.nesdb.go.th/
Passmore, C., & Stewart, J. (2002). A modeling approach to teaching evolutionary biology in high schools. Journal of Research in Science Teaching, 39(3), 185–204. doi:10.1002/tea.10020
Portin, P. (2002). Historical development of the concept of the gene. The Journal of medicine and philosophy, 27(3), 257–86. doi:10.1076/jmep.27.3.257.2980
Posner, G. J., Strike, K. A., Hewson, P. W., & Gertzog, W. A. (1982). Accommodation of a scientific conception: Toward a theory of conceptual change. Science Education, 66(2), 211–227. doi:10.1002/sce.3730660207
Prain, V., & Waldrip, B. (2013). Teachers’ Initial Response to a Representational Focus. In R. Tytler, V. Prain, P. Hubber, & B. Waldrip (Eds.), Constructing representations to learn in science (pp. 15–30). Rotterdam, The Netherlands: Sense Publishers.
Redfield, R. J. (2012). “Why do we have to learn this stuff?”--a new genetics for 21st century students. PLoS biology, 10(7), e1001356. doi:10.1371/journal.pbio.1001356
Reece, J. B., & Campbell, N. A. (2011). Campbell biology (9th ed.). Boston, MA: Benjamin Cummings/Pearson.
Rheinberger, H.-J., & Müller-Wille, S. (2010, October 26). Gene. Retrieved May 23, 2013, from http://plato.stanford.edu/entries/gene/
Roseman, J. E., Caldwell, A., Gogos, A., & Kurth, L. (n.d.). Mapping a coherent learning progression for the molecular basis of heredity. Paper presented at the annual meeting of the National Association for Research in Science Teaching. San Francisco, CA. Retrieved from http://www.project2061.org/publications/articles/papers/narst2006.pdf
Rosenberg, A. (1985). The structure of biological science. Chicago, IL: University of Chicago Press.
Rotbain, Y., Marbach-Ad, G., & Stavy, R. (2006). Effect of bead and illustrations models on high school students’ achievement in molecular genetics. Journal of Research in Science Teaching, 43(5), 500–529. doi:10.1002/tea.20144
Rutherford, F. J., & Ahlgren, A. (1991). Science for all Americans. New York, NY: Oxford University Press.
Saka, A., Cerrah, L., Akdeniz, A. R., & Ayas, A. (2006). A Cross-Age Study of the Understanding of Three Genetic Concepts: How Do They Image the Gene, DNA and Chromosome? Journal of Science Education and Technology, 15(2), 192–202. doi:10.1007/s10956-006-9006-6
215
Sanders, L. R., Borko, H., & Lockard, J. D. (1993). Secondary science teachers’ knowledge base when teaching science courses in and out of their area of certification. Journal of Research in Science Teaching, 30(7), 723–736. doi:10.1002/tea.3660300710
Sarkar, S. (1992). Models of reduction and categories of reductionism. Synthese, 91(3), 167–194. doi:10.1007/BF00413566
Sarkar, S. (1998). Genetics and reductionism. New York, NY: Cambridge University Press.
Saxe, G. B. (1990). Culture and cognitive development: Studies in mathematical understanding. (p. 212). Hillsdale, NJ, England: Lawrence Erlbaum Associates.
Schaffner, K. F. (1969). The Watson-Crick model and reductionism. The British Journal for the Philosophy of Science, 20(4), 325–348.
Schaffner, K. F. (1993). Discovery and Explanation in Biology and Medicine (p. 617). Chicago, IL: University of Chicago Press.
Sfard, A. (1998). On Two Metaphors for Learning and the Dangers of Choosing Just One. Educational Researcher, 27(2), 4–13. doi:10.3102/0013189X027002004
Shavelson, R., Ruiz-Primo, M., & Wiley, E. (2005). Windows into the mind. Higher Education, 49, 413–430. doi:DOI 10.1007/s10734-004-9448-9
Shulman, L. (1986). Those who understand: Knowledge growth in teaching. Educational Researcher, 15(2), 4–14.
Shulman, L. (1987). Knowledge and teaching: Foundations of the new reform. Harvard educational review, 57(1), 1–23.
Skopeliti, I., & Vosniadou, S. (2007). Reasoning with external representations in elementary astronomy. Proceedings of EuroCogSci07.
Sperandeo-Mineo, R. M., Fazio, C., & Tarantino, G. (2006). Pedagogical Content Knowledge Development and Pre-Service Physics Teacher Education: A Case Study. Research in Science Education, 36(3), 235–268. doi:10.1007/s11165-005-9004-3
Spradley, J. P. (1979). The Ethnographic Interview (p. 247). New York, NY: Holt Rinchart and Winston.
Stake, R. E. (1995). The Art of Case Study Research (p. 192). Thousand Oaks, CA: SAGE Publications.
Stake, R. E. (2005). Multiple Case Study Analysis (p. 342). London: The Guilford Press.
216
Sterelny, K., & Griffiths, P. E. (1999). Sex and Death: An Introduction to Philosophy of Biology (p. 440). Chicago, IL: University of Chicago Press.
Stewart, J. (1983). Student problem solving in high school genetics. Science Education, 67(4), 523–540. doi:10.1002/sce.3730670408
Stewart, J., Cartier, J., & Passmore, C. (2005). Developing understanding through model-based inquiry. In . Donovan & J. D. Bransford (Eds.), How students learn science in the classroom (pp. 515–565). Washington, DC: The National Academies Press.
Stewart, J., Hafner, A., & Dale, M. (1990). Students’ alternate views of meiosis. The American Biology Teacher, 52(4), 228–232.
Stewart, J., & Rudolph, J. L. (2001). Considering the nature of scientific problems when designing science curricula. Science Education, 85(3), 207–222. doi:10.1002/sce.1006
Stewart, J., & Van Kirk, J. (1990). Understanding and problem-solving in classical genetics. International Journal of Science Education, 12(5), 575–588. doi:10.1080/0950069900120509
Stocklmayer, S. M., & Treagust, D. F. (1996). Images of electricity: how do novices and experts model electric current? International Journal of Science Education, 18(2), 163–178. doi:10.1080/0950069960180203
The Design-Based Research Collective. (2003). Design-based research: An emerging paradigm for educational inquiry. Educational Researcher, 32(1), 5–8.
The Nation. (2013). Thai students rake in Olympiad medals. The Nation. Retrieved from http://www.nationmultimedia.com/national/Thai-students-win-3-gold-medals-at-physics-Olympia-30210510.html
The World Bank. (2012). Thialnd. In Countries and Economics Data. Rerieved from http://data.worldbank.org/country/thailand
Treagust, D., & Tsui, C. (2013). Multiple representations in biological education (p. 390). New York, NY: Springer.
Tsui, C., & Treagust, D. F. (2004). Conceptual change in learning genetics: an ontological perspective. Research in Science & Technological Education, 22(2), 185–202. doi:10.1080/0263514042000290895
Tsui, C., & Treagust, D. F. (2007). Understanding genetics: Analysis of secondary students’ conceptual status. Journal of Research in Science Teaching, 44(2), 205–235. doi:10.1002/tea
217
Tsui, C.-Y., & Treagust, D. F. (2003). Genetics reasoning with multiple external representations. Research in Science Education, 33(1), 111–135. doi:10.1023/A:1023685706290
Tytler, R., Prain, V., Hubber, P., & Waldrip, B. (2013). Constructing Representations to Learn in Science (p. 209). Rotterdam, The Netherlands: Sense Publishers.
United Nations. (2012). Thailand. In UN Data: A world of Information. Retrieved from http://data.un.org/CountryProfile.aspx?crName=THAILAND
United Nations Children's Fund. (2012). Thailand. In Information by country and programme. Retrieved from http://www.unicef.org/infobycountry/Thailand.html
Van der Meij, J., & de Jong, T. (2006). Supporting students’ learning with multiple representations in a dynamic simulation-based learning environment. Learning and Instruction, 16(3), 199–212. Retrieved from http://www.sciencedirect.com/science/article/pii/S0959475206000260
Van Driel, J. H., Jong, O. De, & Verloop, N. (2002). The development of preservice chemistry teachers’ pedagogical content knowledge. Science Education, 86(4), 572–590. doi:10.1002/sce.10010
Vance, R. (1996). Heroic Antireductionism and Genetics: A Tale of One Science. Philosophy of Science, 63, S36–S45.
Venville, G., Gribble, S. J., & Donovan, J. (2005). An exploration of young children’s understandings of genetics concepts from ontological and epistemological perspectives. Science Education, 89(4), 614–633. doi:10.1002/sce.20061
Venville, G., & Treagust, D. F. (1998). Exploring conceptual change in genetics using a multidimensional interpretive framework. Journal of Research in Science Teaching, 35(9), 1031–1055. doi:10.1002/(SICI)1098-2736(199811)35:9<1031::AID-TEA5>3.0.CO;2-E
Vosniadou, S. (2008). Conceptual change research: An introduction. In Handbook of research on conceptual change. New York, NY: Routledge.
Waters, C. K. (2004). What was classical genetics? Studies in History and Philosophy of Science Part A, 35(4), 783–809. doi:10.1016/j.shpsa.2004.03.018
Waters, C. K. (2008). Molecular Genetics. Retrieved July 20, 2010, from http://plato.stanford.edu/archives/fall2008/entries/molecular-genetics/
Wiggins, G., & McTighe, J. (2005). Understanding by design (2nd ed.). Alexandria, VA: ASCD.
Wood-Robinson, C., Lewis, J., & Leach, J. (2000). Young peoplea’s understanding of the nature of genetic information in the cells of an organism. Journal of Biological Education, 35(1), 29–36. doi:10.1080/00219266.2000.9655732
218
Wynne, C. F., Stewart, J., & Passmore, C. (2001). High school students’ use of meiosis when solving genetics problems. International Journal of Science Education, 23(5), 501–515. doi:10.1080/09500690121597
Yin, R. K. (2009). Case Study Research: Design and Methods (Applied Social Research Methods) (5th ed., p. 240). Thousand Oaks, CA: SAGE Publications.
Zohar, A., & Nemet, F. (2002). Fostering students’ knowledge and argumentation skills through dilemmas in human genetics. Journal of Research in Science Teaching, 39(1), 35–62. doi:10.1002/tea.10008
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APPENDICES
Appendix A: Research Instruments
(1) Questionnaire for Teachers
Developing Pedagogical Tools to Improve Teaching Gene Concept in High School
PART A: General Information For each of the following questions, please check and fill out the responses that best describe you 1. How many years have you been teaching high school science?
1 – 3 years 3 – 5 years 5 – 10 years 10 – 20 years More than 20 years
2. Please specify science subjects/topics you have currently taught (Ex. Biology, Chemistry, Environmental science, etc.):
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
3. What is the highest degree you have earned? High School Diploma B.A./B.S. Masters Ed.D/Ph.D. Others________________________
4. What was your major field of study for the bachelor’s degree? (Ex. Science education, Biology, Education, etc.)
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
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5. Have you have a specific course or training in genetics? Please specify. ______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
PART B: Teaching Genetics 6. In what classes do you teach genetics? For each class, please estimate the overall academic
achievement of students (High, Average, Low, or Mixed levels of achievement). ______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
7. What are textbooks/curriculum/learning kits you use when teaching genetics? ______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
8. How much time in the school year do you devote to classical genetics? (genetic inheritance, Mendel’s law, etc.)
less than 12 hours about 12-16 hours more than 16 hours
9. How much time in the school year do you devote to molecular genetics? (gene expression, DNA replication, protein synthesis, etc.)
less than 16 hours about 16-20 hours more than 20 hours
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10. What do you find the most difficult aspect in teaching high school genetics? Why? ______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
For the statements below, indicate your agreement or disagreement by checking () choices that best expresses what you think about the statement.
The Statement
Strongly Disagree
(1)
Disagree
(2)
Neither Agree or Disagree
(3)
Agree
(4)
Strongly Agree
(5)
11. I know enough about genetic inheritance to teach my class.
12. I know enough about molecular genetics to teach my class.
13. I have a deep understanding of the big ideas and organizing themes in genetics.
14. I am familiar with common student understandings and misconceptions about genetics
15. If a student has difficulty understanding important genetics concepts, I can usually find several different ways to help him/her.
16. I know how to select effective teaching approaches to guide student thinking and learning in genetics.
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(2) Teacher Interview Protocol
Part A: Genetics lesson: 1. Tell me how you plan genetic lessons. Tell me about the curriculum and instructional
materials you use in your genetic class. 2. How do you introduce students about genes? 3. How do you introduce the class when students begin genetic inheritance lesson? 4. How do you introduce the class when students begin molecular genetics lesson? 5. How do you make connection between two units, genetic inheritance lesson and
molecular genetics lesson? 6. What are advantages of the teaching strategies you used in the lessons? 7. Tell me about other factors that influence your teaching about genetics.
Part B: Teachers’ ideas about students’ understanding of the gene: 8. Why is genetics important for student to learn? What do you intend students to learn
about genetics? 9. Reflecting on your experience in teaching genetics, what do you find the most difficult
concept for students to learn? 10. Reflecting on your experience in teaching genetics, what do your students typically know
about the gene when they come to class? What students’ difficulties in understanding genetics do you expect? Can you provide some examples of instructional strategies for promoting students’ understanding of these issues?
11. What do your students typically struggle with when they learn about the gene and its function? What are strategies you used?
Part C: Teachers’ content knowledge: 12. What is a gene? What is the function of the gene? 13. What do you think genes look like? Please draw a representation of genes. 14. How does a gene control genetic trait? 15. Given pictures depicting genes, what does picture A and picture B represent? (Picture A
represents classical gene model and picture B represents molecular gene model.) 16. Is there the relationship between picture A and picture B? Explain how they are (not)
related, what connections are, and what differences are. Draw pictures to illustrate the connection
17. Given representations related to genes, what do these pictures depicted? (see next pages) 18. Given representations related to genes, how do you use these pictures in your teaching
and what are connections between these pictures? (see next pages) Part D: Teachers’ ideas about students’ understanding of multiple models of genes:
19. Given vignettes about students’ ideas about genetics, what kinds of student misconceptions associated with the gene concept have you noticed from examples?
20. Reflecting on presented issue about students’ understanding of multiple models of the gene, why do you think students have difficulty making connection between multiple models of the gene?
21. Have you been challenged with this problem in your class? What are strategies that you used to respond this challenge? Why do you think it worked?
22. How would you respond to presented problem concerning student understanding of multiple models of the gene? What strategies do you think could help students make sense of multiple models of the gene? Why do you think it work?
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AA
Aa
aa
ตนสง
ตนเตย
ตนสง
A
a
A = Dominant allele
a = recessive allele
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ลาดบนวคลโอไทด Nucleotide Sequence
5’ATGGATGTATCATCAAAGGACTTTCAAGGAGCCCGTTGTGTAATAG3’
โครงสรางโปรตน
Protein Structure
Met Asp Val Ser Ser
Lys
Phe
Asp
Gln Gly Gly Pro
Ser
Cys Leu
สายกรดอะมโน
Polypeptide
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Gene
5’ G A C A G T A C T T C A A A C C G A T T C C A T G G 3’
3’ C T G T C A T G A A G T T T G G C T A A G G T A C C 5’
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(3) Guidelines for Group Discussion
Pedagogical Tools for Teaching the Gene Concept Description:
This workshop is a part of a research project: Finding Pedagogical Tools to Improve Teaching Gene Concept in High Schools. The purpose of the research is to develop instructional guidelines to facilitate students’ understanding of multiple models of genes and to enable them to use the appropriate models to explain genetic phenomena meaningfully. Another purpose is to document teachers’ content knowledge and pedagogical strategies regarding the teaching of genetics. This study has been approved by the UW Institutional Review Board.
The targeted participants are a group of 5 to 8 high school biology teachers who have taught high school genetics. In the workshop, participants will be asked to participate in group discussion about student understanding of genes, multiple models of genes, and pedagogy in teaching genetics. Participants will engage in discussion to develop pedagogical tools for teaching genetics.
The workshop consists of two sessions: Teachers’ Pedagogical Content Knowledge and Developing Tools for Teaching Genetics. Each session will be last approximately 3 hours (9:00am to 12:00pm), and it will be held on the date that is convenient to the participants at the Institution for the Promotion of Teaching Science and Technology. Food and drinks will be provided during the workshop. See more details about activity schedule in the following table.
The importance of the study: While knowledge of genetics is a cornerstone of biology, genetics is challenging to both
students and teachers. My previous study and other research (Tsui & Treagust, 2004; Venville & Treagust, 1998) has showed that even after genetics instruction students have difficulty understanding the nature and function of genes meaningfully.
To explain complex scientific phenomena, scientists use models which are simplifications of complex phenomena to make abstraction visible. Multiple scientific models of genes have been used to serve particular functions for explaining phenomena. These multiple models of genes are also presented in high school genetics. The research however showed that most high school students viewed genes as particles that get pass from parents, and only a few students conceptualized genes as sequences of instructions. The findings also revealed that those students who did not demonstrate knowledge of the molecular gene model struggled to provide explanations about gene expression.
A gene concept is a fundamental for understanding core concepts such as genetic inheritance, gene expression, and genetic variation, including making sense of the roles of genetic information and biotechnology around us today. The current high school genetic curriculum, however, has failed to facilitate most students to conceptualize multiple models of genes. This problem leads to the question of this study: What are strategies to facilitate students to make sense of multiple models of the gene and use appropriate models to explain genetic phenomena?
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Time Topic Activity
Session 1: Teachers’ Pedagogical Content Knowledge
9.00-9.15 (15 minutes)
Introduction - Explanation about the study and its purposes. - Participants introduce themselves to a group.
9.15- 11:00 (1.45 hours)
Student understanding of genes
- Activity: explore teachers’ content knowledge of genes.
- Presentation: examples of students’ conceptions of genes and multiple scientific models.
- Discussion in group: teachers’ ideas about students’ understanding of genes and multiple models of genes.
Teachers’ content knowledge of genes - Participants complete the survey containing following questions.
1. What is a gene? 2. What do you think genes look like? Draw a picture of genes. 3. What is the function of the gene? 4. How can a gene cause a genetic disease?
- Discuss with the group: ‘How do you think students may answer these questions?’ Teachers’ ideas about students’ understanding of genes - Discuss the following question in a group.
1. Why do you think genetics is important for student to learn? 2. Reflecting on your experience in teaching genetics, what do you find the most difficult
concept to learn? 3. Reflecting on your experience in teaching genetics, what do your students typically
know about the gene when they come to class? 4. What do your students typically struggle with when they study the gene and its
function? Teachers’ ideas about multiple models of genes - Presentation examples of students’ conceptions of genes and multiple scientific models of genes and ask following leading questions.
1. How do you think students may answer the questions in ‘What is a gene’ questionnaire?
2. What kinds of student misconceptions associated with the gene concept have you noticed from examples?
3. Reflecting on presented issue about students’ understanding of multiple models of genes, why do you think students have difficulty making connection between multiple models of the gene?
4. Have you been challenged with this problem in your class? Explain. 11:00-12:00 (60 minutes)
Teaching genetics - Discussion in group: pedagogy, strategy, materials teachers use in the class.
- Discussion in group: suggestions on pedagogical tool to teach multiple models of genes.
Pedagogy, strategy, and materials to solve the problem from teachers’ ideas - Participants discuss about instructional materials and strategies they use according to the following questions.
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Time Topic Activity 1. How do you normally introduce students about the gene? In which lessons? 2. How do you introduce students about the gene as sequence of instruction when students
begin molecular genetics lesson? 3. How do you make connection between multiple models of the gene? 4. What are advantages of the teaching strategies you used in the lesson (both in general
and specific to multiple models of genes)? 5. How would you respond to the presented problem concerning student understanding of
multiple models of the gene? 6. What strategies do you think could help students make sense of multiple models of the
gene? Why do you think it work? 7. What is the classical gene model? What is the molecular gene model? What are
similarity and differences between the models? Break 10:30-10:40 (10 minutes)
Session 2: Developing tools for teaching genetics
9:00 -11.30 (2.30 hours)
Introducing tools & Developing pedagogical tools
- Presentation: initial ideas of tools to teach genes Activity 1: multiple-linked representations Activity 2: solving the problems using multiple models in different contexts
- Discussion in group: comments on how to improve the designed tools.
Activity 1 - multiple-linked representation - Participants discuss in group about presented examples of multiple-linked representation.
1. Do you think whether the activity help students to make connections between the classical model and the molecular model? Why?
2. When do you think the activity should be introduced? 3. How would you use the activity in your classroom? In which lesson? 4. What are strengths and weakness of this activity? 5. How do you think these activities should be improved?
Activity 2 – multiple models of genes - Participants discuss in group about example problems that require students to use multiple models of genes in solving the problems.
1. After you solve the genetic problems that required multiple models to solve problems in different contexts, answer the following questions. How could this activity be used in the classroom? When should this activity be introduced in the lesson?
2. How do you think these activities should be improved? 3. Will you consider using these activities in your classroom? Why?
11:30-12:00 (30 minutes)
Reflection - Written comments about the workshop.
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(4) Follow-up Interview Protocol
Part A: Teaching
1. Compare your teaching with other teachers. What are similarities or differences?
2. Compare your teaching when you use activities and when you did not use the activities.
3. Tell me how is your teaching change after you use the activities
4. How do you think your knowledge has changed, comparing to before participating
research?
5. If you plan to use the activities again, what would you like to change?
6. How would you prepare for teaching again?
Part B: Student learning
7. Do you think what students learn from the activities?
8. Do you think the activities help students have better understanding of genetics? How?
9. What difficulties did you experience in your teaching?
10. How do the activities help you explore students’ idea?
11. What questions did you get during the activities? How did you response?
Part C: Leaning activities
12. What changes would you make in these lessons next time?
13. How do the tools work in the classroom?
14. Do you think the activities could be used with other schools?
15. Do you have any recommendations or questions?
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(5) Student Interview Protocol
Part A: Learning genetics 1. Why do you think genetics is importance for you? Why do you have to learn genetics? 2. What majors do you plan to enter after graduating high school? 3. Reflecting on your experience, what do you find the most difficult concept to learn? 4. Reflecting on your experience, what genetics topics that you think you understand well? 5. What do you think about your teacher’s teaching method? What are activities or topics
that you remember? Part B: Genetic Inheritance
6. Give an example of a genetic trait and an example of a non-genetic trait. Explain. 7. What are criteria that you use to categorize a genetic trait and a non-genetic trait? 8. What are causes of a genetic trait? 9. How does a gene control genetic trait? Do you think a normal individual will have this
gene or not? Part C: The Gene
10. What is a gene? What do you think genes look like? Please draw a picture of a gene. 11. Given pictures depicting genes, what does picture A and picture B represent? (Picture A
represents classical gene model and picture B represents molecular gene model.) 12. Is there the relationship between picture A and picture B? Explain how they are (not)
related, what connections are, and what differences are. 13. What is the function of a gene? How does a gene control genetic trait? 14. What is the genetic information?
Part D: Probability of Genotype Students are given a set of pictures of flowers and alleles to demonstrate a pattern of inheritance of the flower color of a plant. Giving phenotypes of parents and F1 generations [Parents= Blue (Aa) x Yellow (aa) and F1 generation = 4 Blue and 3 Yellow (aa)].
15. What is the dominant allele? How do you know? 16. Find genotype and a genotype ratio of F1 (Do you want any additional information?) 17. If Blue in F1 cross with another Blue in F1, what are phenotypes of the next generation? 18. Why does the next generation have yellow flowers? 19. Explain processes of genetic inheritance at the cellular level.
Part E: Protein synthesis Students are given a set of pictures of base sequences to build DNA sequence and RNA sequence.
20. Given a DNA template that control the flower color (3’TAC CCA AGA TTG ATA ACT 5’), find a polypeptide sequence.
21. Explain processes of protein synthesis at the cellular level. Where do these processes happen? What happen to a translated polypeptide after translation?
22. What is a protein? How do cells make this protein? What roles do proteins have in organisms?
23. If the given DNA sequence is a dominant gene, do you think a DNA sequence of a recessive gene will be similar of different?
24. If a plant is aa, do you think it will produce the same protein with AA? Why? How does a difference of a recessive gene influence its characteristics?
25. Explain the activity 3: gene expression of pea plant.
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Appendix B: Designed Learning Materials
(A1) Representations of Genetic Material
Direction: Please answer the following questions about representations of a gene as well as you
can (You can use examples and draw pictures to explain your ideas, if you find them helpful).
1. What does picture A represent? Explain the meanings of the pictures.
Picture ‘A’
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
2. What does picture B represent?
Picture B
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
R r
3’ … G A C A G T A C T T C A A A C C G A T T C C A T G
5’ … C T G T C A T G A A G T T T G G C T A A G G T A C
Gene
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3. Is there the relationship between picture A and picture B? Why? Explain how they are(not) related, what are connections, and what are differences. (Draw pictures to illustrate the connection in the area below, if you find them helpful).
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
4. Use both pictures to explain: What is a gene? And What is the function of a gene?
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
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(A2) Explain the Scenarios about Genetics
Direction: Discuss with your group to explain the scenarios related to genetics. Ben is a new student who has just learned about genetics. His teacher asks him to explain the following problems about genetics. Your task is to help him select the pictures of genetic material that can help him to explain the scenarios. Each group of students will be given the scenarios about genetics phenomena and pictures of genetic materials. Discuss with your group to select pictures that you need in order to solve the problems. You can use more than one picture if you need to.
Think about how you would answer the questions, what each picture means, and why you use (or do not use) those pictures to answer the questions. Write down your group’s answer and prepare to present scenario and answer to the class. You will have time about 20 minutes to complete the task. Question 1: A fisherman has a clam farm where he mates and cultivates clams in order to sell them in the market. He observed that people now like to buy the black clam more than the white clam. He therefore plans to breed more black clams to sell more clams. He mates black clams together; however, he found that he also get some white clams. Why does a fisherman get some white clams although the parent claims are both black? Question 2: A scientist studies why the color of shell of this species of clam has different colors, both black and white colors. The color of shell is because of a production of pigment. Based on the comparison of pigment synthesis between black and white shells, the scientist found that a protein that is needed to make the pigment has different structure and shape. The protein in white shell cannot function normally, so there is no pigment produce. Why are the structures of proteins in white and black shells different? Question 3: An ecologist observed the coast near factories and found that the seashell population near that area is white, which differs from the population in other areas where the shells are black. He found that there is a chemical that leaks from the factory in the body of clams, and it results in a change in clam’s genes called a mutation. How does this mutation affect the color of the shell? Question 4: A scientist extracts DNA from a clam and found that the nucleotide sequence of that clam is AAAGGCTTCTCC and the gene on both chromosomes has the same alleles. What are the genotype and the phenotype of this shell? Question 5: A scientist performs a breeding experiment and identifies a black clam with a genotype Aa. Why does this clam a have black shell? How does the amino acid sequence of this heterozygous clam differ from the white clam?
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DNA of Black shell … A A A G G C T T C T C C … DNA of White shell … A A A G G C T C C T C C …
A = Dominant allele
a = recessive allele
Picture 01
A
a
A = Dominant allele
a = recessive allele
White Shell
Black Shell
Picture 02
Picture 03 Picture 04
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Picture 05 Picture 06
Protein controls dark color
Non-functioning protein
DNA of Black shell
… A A A G G C T T C T C C …
mRNA
… U U U C C G A A G A G G …
Polypeptide
… Phe - Pro - Lys - Agr …
Picture 07
A a A a
A A A a A a a a
AA Aa Aa aa Offspring
Picture 08
Parents
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(A3) Gene Expression of Pea Plant
Gregor Mendel studied genetic inheritance of pea plants since 150 year ago, such as seed
colors, heights, and flower colors. In 1990, a group of scientists began to study protein synthesis
of the color of pea flower. In 2010, a group of scientists identified a nucleotide sequence for pea
flower color and studied how the gene controls the color of flower. They found that purple
flowers produce a protein to regulate anthocyanin pigment production that is responsible for the
purple color.
The color of flower of pea plant is a genetic trait controlled by a gene at one locus. In pea
plant, the dominant allele (A) causes the purple flower, whereas the recessive allele (a) causes
the white flower. When they studied gene expression of flower color, they found that the purple
flower is a result of a purple pigment called anthocyanin in petals. The production of
anthocyanin is a chain reaction depending on many enzymes. Gene A, that Mendal studied,
controls the synthesis of an enzyme called chalcone synthase. This enzyme is a first enzyme
functions in synthesis process of anthocyanin, leading to purple petals flower in pea plants as
shown in a following picture.
Note: Providing nucleotide sequences are only examples, because real nucleotide sequences contain multiple base pairs
Enzyme A (chalcone synthase)
Gene A
X Anthocyanin Y Z
Enzyme B
Gene B
Enzyme C
Gene C
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What is genotype and phenotype of homozygous dominant?
Answer:_____________________________________________________________________ A diagram below shows how the purple flower in homozygous dominant is determined by the
gene (allele A).
A
A
Step2: Transcription
Step 1: Uncoiled
Regulate pigment production
DNA sequence
3’ ... T A C G C T G A A A C C C C T A T T... 5’
mRNA
5’ ... A U G C G A C U U U G G G G A U A A... 3’
Step 3: Translation
Met Arg Leu Trp Gly Polypeptide
Protein
Purple pigments
Protein synthesis
Step 4: Protein
Step 5: Regulating pigment
238
In contrast, the white flower has different version of a gene, in which 1 base in DNA is
changed from C to T leads to changing from amino acid (Tryptophan) to the stop codon (mRNA
sequence = 3’ A U G C G A C U U U G A G G A... 5’). White flower plants produce a
malfunction protein that cannot regulate anthocyanin pigment production, so purple pigments are
not produced.
**Fill the blank and draw pictures that show all of the steps in gene expression of homozygous recessive pea plant.
Step2: Transcription
Step 1: Uncoiled
Cannot regulate pigment
production
DNA sequence
3’ ... T A C G C T G A A A C T C C T A T T... 5’
mRNA
5’ ... A U G C G A C U U U G A G G A U A A... 3’
Step 3: Translation
Polypeptide
No Anthocyanin
Protein Synthesis Step 4: Protein
Step 5: Regulating pigment
Malfunctioned Enzyme A
Gene a
X No Anthocyanin Y Z
Malfunctioned Protein
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What is genotype and phenotype of heterozygous recessive?
Answer:_____________________________________________________________________
**Fill the blank and draw pictures that show all of the steps in gene expression of heterozygous
recessive pea plant.
Step2: Transcription
DNA sequnce
3’ ... T A C G C T G A A A C C C C T A T T... 5’
mRNA
Step 3: Translation
Met Arg Leu Trp Gly
Polypeptide
mRNA
5’ ... A U G C G A C U U U G A G G A U A A... 3’
Genotype
DNA sequnce Step 1: Uncoiled
Step 4: Protein
Step 5: Regulating pigment
Protein: Does it have normal structure & function?
Polypeptide
Protein: Does it have normal structure& function?
Phenotype?
Produce pigment?
Produce pigment?
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(A4) Building Your Own Protein
Each pair of students will be provided 12 pieces of ribbon coils of various colors and one
4-foot toober to build a protein structure. The toober represents the backbone of the protein.
The colored tacks represent the amino acids. Refer to the following chart regarding which tack
color indicates the type of amino acid.
TACK COLOR and number TYPE OF AMINO ACID Blue (2) Basic amino acid ( + charge ) Red (2) Acidic amino acid ( - charge)
Yellow (6) Hydrophobic amino acid White (3) Polar (hydrophilic) amino acid Green (2) Cysteine amino acid
INSTRUCTIONS
1. Place each of your 12 tacks randomly but evenly along the toober. By doing this, the tacked
toober represents a protein made of 12 amino acids.
2. Fold the protein according to the rules of chemistry that drive protein folding (see next page).
3. Compare the structure of your protein with proteins made by your friend
4. Try mutating your protein by changing sequence of tacks and refolding it. (For example,
mutate one of the hydrophobic to a positively charged amino acid ) How does it look now?
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The activity is adapted from the Center for BioMolecular Modeling.
Questions: Please answer these questions after you have completed the activity.
1. Compare the structure of your protein with proteins made by your friends
………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. 2. Thinking about your original folded protein, would it change if you switched the order of just two of the tacks? Why or why not? ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. 3. Why do you think the structure of a protein is so important? ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. …………………………………………………………………………………………………..
Bascic Laws of Chemistry that Drive Protein Folding
1. Hydrophobic sidechains (yellow tacks) will be buried on the inside of the globular protein, where they are hidden from polar water molecules.
2. Charged sidechains (blue and red tacks) will be on the surface of proteins where they
often neutralize each other and from salt bridges.
3. Polar sidechains (white tacks) will be on the surface of the protein where they can hydrogen bond with water.
4. Cysteine sidechains (green tacks) often interact with each other to form covalent disulfide
bonds that stabilize protein structure.
242
Feather color in bird is determined by a single gene with multiple alleles, which is similar
to human blood type that controlled by three alleles (IA, IB, i) and individuals have a combination
of two alleles. Feather color is controlled by four alleles as shown below. Black, grey and red
colors are controlled by dominant alleles and white color is determined by recessive allele.
Nucleotide sequences of each allele are different. Multiple allele of feather color leads to
variation in bird population.
Direction: Dividing students into 4 groups to study structures of proteins controlled by
different genes. Each group selects one sequence of nucleotides. Transcribe and translate to a
sequence of amino acids. Build and fold the protein according to the DNA sequence.
Color Allele mRNA Sequence
Black
IB
UGG GCA UGC AGA UUU UGU ACC GAU
Grey
IG
UGG CAU UGC AGA UUU UGU ACC AAA
Red
IR
UAU GCA GGG AGA UUU UGU GAU UCC
White
i
UAU GCA CUU CCC UGC AGA UUU UGU
243
Phenotype _______________________ DNA Sequence mRNA sequence Amino acid sequence
Compare the structure of your protein with proteins made by your friend
………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. Explain how differences of nucleotide sequences of gene for feather color influence differences in phenotype? ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. Finding genotypes and phenotypes of offspring from the parents that have following genotypes: a) IBi x IBi and b) IGi x ii ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. …………………………………………………………………………………………………..
transcription
translation