bridging the silos: opening a connection between physics and biology instruction
DESCRIPTION
A presentation for BioQuest 2014 (University of Delaware) describing NEXUS/Physics: an introductory physics course designed to serve life science students and to explicitly articulate with a biology curriculumTRANSCRIPT
Bridging the silos: Opening a Connection
Between Physics and Biology Instruction
Edward (Joe) Redish University of Maryland 6/21/14
BioQuest 2014 1
Building a physics course for biology majors: Some questions
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Is it possible for a physics course for bio majors to “fit in”? Can it articulate effectively with the biology, chemistry, and math that bio students take? How do disciplinary differences effect what and how we ought to teach? What do we learn about these issues from Discipline-Based Education Research?
Outline
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Context: NEXUS/Physics: Content: Fitting into the Curriculum Cognition: The Resources Framework
Concepts: KiP Epistemology
Culture: The communication divide Implication for Instruction: Teaching physics standing on your head
NEXUS/Physics
Context
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BioQuest 2014
In the summer of 2010, HHMI offered four universities the opportunity to:
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Develop prototype materials for biologists and pre-meds in
Chemistry (Purdue) Math (UMBC) Physics (UMCP) Capstone case study course (U of Miami)
that would take an interdisciplinary perspective
be competency based 6/21/14 BioQuest 2014
Change the goals of the course
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Traditional physics is “just physics”: it ignores the needs and interests of bio students. We want to serve biology students and faculty by articulating with the biology curriculum
Provide support for difficult physics concepts that they will encounter in bio and chem classes.
Use methods common in intro physics Use simplified models to build understanding, Build a sense of physical mechanism, Develop coherences between things that initially seem contradictory, etc.
Changing the culture of the course
Seek content and examples that have authentic value for the biology curriculum.
Students should see the course as helping them understand things are important for learning biology. Faculty teaching upper division biology (and chemistry) should want physics as a pre-requisite.
Assume this is a 2nd year college course. Biology, chemistry, and calculus are pre-requisites.
Use interactive engagement pedagogy.
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Redish et al., Am. J. Phys 82:5 (2014) 368-377
The NEXUS/Physics timeline: Iterative research based design
2010-11 Extensive discussion and negotiation among stakeholders.
2011-12 Create on-line reading materials, problems Teach a small test class (N ~ 20)
2012-13 Refine and expand materials Team teach two small flipped classes (N ~ 20) Create new laboratories
2013-14 Becomes the required course for all bio majors. Fall: Deliver in two large lectures (N ~ 120): instructors from the design team.
Spring: Teach both section in 4 large lectures with 4 new instructions.
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Detailed research on student responses – observation, interviews, surveys
Fitting with the biology curriculum
Content
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BioQuest 2014
Interdisciplinarity: Rethink the content from the ground up
Choose content that articulates with required introductory biology and chemistry classes. Cover physics that helps students develop insight into important biological ideas. Suppress traditional content of little value. But ... This is a course in which students are expected to learn the physics – and see how it can be of value to biology. It is NOT “physics add-ons for biologists.”
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New interdisciplinary topics
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Focus on modeling and explicating assumptions. Do micro and macro examples throughout assuming students know about atoms. Include discussion of chemical energy and reactions Treat random motion as well as coherent. (Labs!) Carefully build the basic statistical mechanics support for thermodynamics (conceptually). Expand treatment of fluids and physics in fluids.
Dreyfus et al., Am. J. Phys 82:5 (2014) 403-411 Geller et al., Am. J. Phys 82:5 (2014) 394-402 Moore et al., Am. J. Phys 82:5 (2014) 387-393
Example: Chemical bonding – A bridge through interdisciplinary reconciliation
In introductory chemistry and biology classes, students learn about chemical reactions and the critical role of energy made available by molecular rearrangements. But students learn heuristics by rote that can feel contradictory to them and that they often don’t know how to reconcile.
1. It takes energy to break a chemical bond. 2. Breaking the bond in ATP is the “energy currency”
providing energy for cellular metabolism.
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W. C. Galley, J. Chem. Ed., 81:4 (2004) 523-525.
M. Cooper and M. Klymkowsky, CBE Life Sci Educ 12:2 (2013) 306-312
Many students infer a “piñata” model of a chemical bond.
"But like the way that I was thinking of it, I don't know why, but whenever chemistry taught us like exothermic, endothermic, like what she said, I always imagined like the breaking of the bonds has like these little [energy] molecules that float out, but like I know it’s wrong. But that's just how I pictured it from the beginning."
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From student responses we learned a useful perspective on multi-disciplinary reconciliation.
Gregor: I put that when the bond's broken it releases energy. Even though I know... that obviously that's not an energy-releasing mechanism. ...you always need to put energy in, even if it’s like a really small amount of energy to break a bond. Yeah, but like. I guess that's the difference between like how a biologist is trained to think, in like a larger context and how physicists just focus on sort of one little thing....I answered that it releases energy, but it releases energy because when an interaction with other molecules, like water...and then it creates like an inorganic phosphate molecule that has a lot of resonance. And is much more stable than the original ATP molecule. So like, in the end releases a lot of energy, but it does require like a really small input of energy to break
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B. Dreyfus, et al., “Students' reasoning about 'high-energy bonds' and ATP: A Vision of Interdisciplinary Education” Phys. Rev. ST-PER 10 (2014) 010115.
Distinct disciplinary perspectives
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Gregor is right! Physicists and biologists (and chemists) make different tacit assumptions. Physicists tend to isolate to focus on a particular physical phenomenon and mechanism. Biologists (and chemists, sometimes) tend to assume the natural and universal context of life – a fluid environment (air and water taken for granted).
Approach
1. Introduce atoms and molecules early in the class, with quantification and estimation to build a sense of scale.
2. Introduce concept of “binding energy” in standard macroscopic energy contexts (skateboarder in a dip)
3. Create a chain of tasks in atomic and macroscopic contexts for learning to read and interpret potential energy graphs.
4. Refine tasks by observation of student responses and negotiation among physicists, biologists, and chemists.
5. Be explicit about the value of different disciplinary perspectives, bridging the different two perspectives.
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6/21/14 BioQuest 2014 B. Dreyfus, et al., “Chemical energy in an introductory physics course for the life sciences”, Am. J. Phys. (May 2014).
Midterm 17
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Two students discussing the process of ATP hydrolysis (ATP + H2O ADP + Pi) make the following comments: Justin: “The O-P bond in ATP is called a ‘high-energy bond’ because the energy released when ATP is hydrolyzed is large. That released energy can be used to do useful things in the body that require energy, like making a muscle contract.” Kim: “I thought chemical bonds like the O-P bond in ATP could be modeled by a potential energy curve like this, where r is the distance between the O and the P. If that’s the case, then breaking the O-P bond in ATP would require me to input energy. I might not have to input much energy to break it, if that O-P happens to be a weak bond, but shouldn’t I have to input at least some energy?” How did Kim infer from the PE graph that breaking the O-P bond requires an input of energy? Who’s right? Or can you reconcile their statements?
The Resources Framework
Cognition
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BioQuest 2014
Key cognitive foothold ideas
1. People have a huge store of long-term memories
2. Items in memory are associated and can activate or inhibit each other.
3. Memory is reconstructive and dynamic. 4. Working memory is limited. 5. Access to long-term memory
is controlled by executive function.
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Redish & Smith, J. of Eng. Educ 97 (2008) 295-307
The Resources Framework: A multi-level structure
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Concept knowledge (basic knowledge) Compilation and chunking Knowledge organization (associations)
Knowledge about when to use knowledge (switching mechanisms or control structures)
Cultural knowledge Framing Epistemology
Affect (emotional response) Feelings (fear, self confidence, aesthetics) Motivation Identity
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Level 1: Knowledge in Pieces: Concepts based on embodied experience
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Phenomenological primitives (observed) Reasoning primitives (descriptive/inferred) Associational patterns
Redish, Fermi Summer School CLVI (2003) Sabella & Redish, Am. J. Phys. 75 (2007) 1017-1029
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Example: Why do we have seasons?
Essentially every elementary school student in the USA has been given the explanation.
Then why do Harvard graduates give the wrong answer when asked?
R-Prim: Closer is stronger / more effective (neither right nor wrong) P-prim: You can get warmer by standing closer to the fire.(right) Associational p-prim: It’s warmer in the summer, so we must be closer to the source of the heat.(wrong)
A Private Universe, http://www.learner.org/resources/series28.html
Level 2: Switching mechanisms: Framing and epistemology
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The limitations of working memory make social knowledge and perception of the learning environment critical. “Of all that I know, what should I use right now?” Framing
Answers the question: “What’s going on here?” (calling on experience and expectations)
Epistemology The study of answering the questions: “What’s the nature of the knowledge we are learning?” and “What are we supposed to do in order to learn it?”
Structures and concepts useful for analyzing epistemological issues
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Warrants Specific statements explaining why a particular claim is true using specific reasoning.
Epistemological resources (e-resources) Generalized categories of “How do we know?” warrants.
Epistemological framing The process of deciding what e-resources are relevant to the current task. (NOT necessarily a conscious process.)
Epistemological stances A coherent set of e-resources commonly activated together in a particular circumstance
Bing & Redish, Phys. Rev. ST-PER 5 (2009) 020108; Phys. Rev. ST-PER 8 (2012) 010105. Tuminaro & Redish, Phys. Rev. ST-PER 3 (2007) 020101.
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Can a fine-grained analysis of disciplinary-specific epistemological resources, framing, and stances help us create better instructional environments and practices in physics for biology students?
The Communication Divide
Culture
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BioQuest 2014
Disciplinary expectations leads to epistemological framing
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Students choose a field, in part, because they have some expectations about what it does and how it functions. In becoming disciplinary experts, students learn the methods and ways of thinking of their discipline. These two sets of understandings do not necessarily match, nor match with those of their (outside of discipline) instructors in service courses.
Epistemological resources
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Knowledgeconstructed
from experience and perception (p-prims)
is trustworthy
Algorithmic computational steps lead to a trustable
result
Information from an authoritative
source can be trusted
A mathematical symbolic representation faithfully
characterizes some feature of the physical or geometric
system it is intended to represent.
Mathematics and mathematical manipulations
have a regularityand reliability and are
consistent across different situations.
Highly simplified examples can yield
insight into complex mathematical
representations
IntroPhysicscontext
Epistemological resources (short names)
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Knowledgeconstructed
from experience and perception (p-prims)
is trustworthy
Algorithmic computational steps lead to a trustable
result
Information from an authoritative
source can be trusted
A mathematical symbolic representation faithfully
characterizes some feature of the physical or geometric
system it is intended to represent.
Mathematics and mathematical manipulations
have a regularityand reliability and are
consistent across different situations.
Highly simplified examples can yield
insight into complex mathematical
representations
Physical intuition (experience & perception)
Calculationcan be trusted
By trusted authority
Physical mapping to math
(Thinking with math)
Mathematical consistency
(If the math is the same, the analogy is good.)
Value of toy models
IntroPhysicscontext
Example:
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An engineering student is asked about something he hasn’t studied yet: pressure under water. His intuition is that the pressure increases as you go deeper. But when he’s given the equation: he gets a sign wrong and concludes the pressure must decrease as you go deeper.
p = p0 + ρgh
Gupta & Elby , Int. J. Sci. Ed 33:18 (2011) 2463-2488
Epistemology is dynamic and responds to a variety of expectations.
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Analyzing the framing shift of an engineering student to a physics problem he had not seen before.
• Coordinated math and intuition
• Positive affect
IntroBiologycontext
Epistemological resources
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Knowledgeconstructed
from experience and perception (p-prims)
is trustworthy
Information from an authoritative
source can be trusted
The historical fact of natural selection leads
to strong structure-function relationships
in living organisms
Many distinct components of
organisms need to be identified
Comparison of related organisms yields
insight
There are broad principles that govern
multiple situations
Living organisms are complex and require multiple
related processes to maintain life
IntroBiologycontext
Epistemological resources (short names)
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Knowledgeconstructed
from experience and perception (p-prims)
is trustworthy
Physical intuition (experience & perception)
Information from an authoritative
source can be trusted
By trusted authority
The historical fact of natural selection leads
to strong structure-function relationships
in living organisms
Many distinct components of
organisms need to be identified
Comparison of related organisms yields
insight
Learning a large vocabulary
is useful
Categorization and classification
(phylogeny)
There are broad principles that govern
multiple situationsHeuristics
Living organisms are complex and require multiple
related processes to maintain life
Life is complex(system thinking)
Note:
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These groupings of resources are labeled as “Intro Bio” and “Intro Physics.” This is to indicate that these are epistemological resources commonly perceived by students as relevant in their intro classes in these subjects. Professionals in both fields tend to use both of these sets resources (though with different distributions and depending on sub-field).
Some examples from Bio
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Biology III: Organismal Biology A principles-based class that structures the traditional “forced march through the phyla” of a biological diversity class.
Some of the principles: Common ancestry (deep molecular homology) Individual evolved historical path) (divergent structure-function relationships) Constrained by universal chemical and physical laws.
Uses Group Active Engagement (GAE) lessons (including math!)
“Todd the biologist”
Ashley’s response to the use of math in Org Bio
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Discussing the use of Fick’s Law in controlling diffusion through a membrane of different thicknesses.
I don’t like to think of biology in terms of numbers and variables…. biology is supposed to be tangible, perceivable, and to put it in terms of letters and variables is just very unappealing to me…. Come time for the exam, obviously I’m going to look at those equations and figure them out and memorize them, but I just really don’t like them. I think of it as it would happen in real life. Like if you had a thick membrane and tried to put something through it, the thicker it is, obviously the slower it’s going to go through. But if you want me to think of it as “this is x and that’s D and this is t”, I can’t do it.
x2 = 2Dt
Another response of a student to math in Org Bio
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The small wooden horse supported on dowels stands with no trouble. When all dimensions are doubled, however, the larger dowels break, unable to support the weight.
Watkins & Elby, CBE-LSE 12 (2013) 274-286.
The little one and the big one, I never actually fully understood why that was. I mean, I remember watching a Bill Nye episode about that, like they built a big model of an ant and it couldn’t even stand. But, I mean, visually I knew that it doesn’t work when you make little things big, but I never had anyone explain to me that there’s a mathematical relationship between that, and that was really helpful to just my general understanding of the world. It was, like, mind-boggling.
Ashley’s dynamic switch
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“Biological authenticity” – • Coordinated math and intuition • In a biological context • Positive affect • Significant value for
understanding biology
Recitation task: Why do bilayers form?
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Prompt: Which term wins?
Prompt: …explain how phospholipids can spontaneously self-assemble into a lipid bilayer…why this particular shape?
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Hollis: I mean, in terms of like bio and biochem, the reason why it forms a bilayer is because polar molecules need to get from the outside to the inside ... so you need a polar environment inside the cell. But I don't know how that makes sense in terms of physics. So... Cindy: So like what I'm saying is, you have to have, like if it's hydrophobic and interacting with water, then it's going to create a positive Gibb's free energy, so it won't be spontaneous. So, in this case, you have the hydrophobic tails interacting with whatever's on the inside of the cell, which is mostly water, right? Hollis: Or other polar molecules. Cindy: Yeah, other polar molecules. It's going to have, and that's bad ... That's a positive Gibb's free energy. Hollis: Yes. See, you explained it perfectly ... Cause I was thinking that, but I wasn't thinking it in terms of physics. And you said it in terms of physics, so, it matched with bio.
Disciplinary epistemologies
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“in terms of bio, the reason why it forms a bilayer is because polar molecules need to get from the outside to the inside” “ if it’s hydrophobic and interacting with water, then it's going to create a positive Gibb's free energy, so it won't be spontaneous and that’s bad..”
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IntroBiologycontext
Physical mapping to math
(Thinking with math)
Satisfaction(smile,
fist pump)
Interdisciplinary coherence
seeking
“Interdisciplinary coherence” – • Coordinated resources from
intro physics and biology • Blended context • Positive affect
Teaching Physics standing on your head
Implications for Instruction
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BioQuest 2014
Does such an analysis help?
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An epistemological analysis provides a finer-grained approach to understanding student responses to instruction. That might help us to better understand interdisciplinary communication and to helping us design more effective instructional environments.
What’s wrong with physics teaching? The “go-to” e-resource
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The epistemological stances naturally taken by physics instructors and biology students may be dramatically different – even in the context of a physics class. One example from my observations of other faculty teaching NEXUS/Physics yields an insight.
The figure shows the PE of two interacting atoms as a function of their relative separation Is the force between the atoms at the separations marked A,B, and C attractive, repulsive, or zero?
C
B A Total energy
r
Potential Energy
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How two different professors explained when students got stuck on this.
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Remember! (or in 1D) At C, the slope of the U graph is positive. Therefore the force is negative – points to smaller r. So the potential represents an attractive force when the atoms are at separation C.
F = −∇U F = − dU
dr
This figure was not actually drawn on the board by either instructor.
Wandering around the class while the students were considering the problem, I found a good response with a different approach.
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A hill is a good analogy for PE Think about it as if it were a ball on a hill. Which way would it roll? Why? What’s the slope at that point? What’s the force? How does this relate to the equation
F = − dU
dr
A conflict between the epistemological stances of instructor and student make things more difficult.
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Calculationcan be trusted
By trusted authority
Physical mapping
to math(Thinking with math)
Physical intuition (experience & perception)
Physical mapping to math
(Thinking with math)
Mathematical consistency
(If the math is the same, the analogy is good.)
Physics instructors seem more comfortable beginning with familiar equations – which we use not only to calculate with, but to code and remind us of conceptual knowledge.
Most biology students lack the experience blending math and conceptual knowledge, so they are more comfortable beginning with physical intuitions.
Teaching physics standing on your head
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For physicists, math is the “go to” epistemological resource – the one activated first and the one brought in to support intuitions and results developed in other ways. For biology students, the math is decidedly secondary. Teleology (structure/function) tends to be their “go to” resource. Part of our goal in teaching physics to second year biologists is to improve their understanding of the potential value of mathematical modeling. This means teaching it rather than assuming it.
So does it work? One student mulls on making sense of force and energy in enzymatic reactions.
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I mean cause, you get this equation in chemistry and biology and now in this class. But you learn it from all different ways, all different angles. And I feel like in this class it’s so much combined with biology you have to put those two realms together...[I: And this is an example of opposite or coming together?] Coming together. Definitely. Cause like in bio you’re always like, “Oh, delta G is how much free energy you have to do work in the system.” And now in this class you actually have a specific definition of what work actually is. Instead of just like, “Oh, it can make this product,” but you can see that, like, how an enzyme fits into what work is. ΔG = ΔH −TΔS
ΔH = ΔU + pΔV
What you need to do multidisciplinary instructional development
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Understand that disciplines take different perspectives on the world – for good reasons. Respect what each discipline brings to the table. Respect students’ disciplinary perceptions of themselves and the knowledge and perspectives they bring to each class. Create stable and longstanding conversations with your colleagues in other disciplines!
Redish & Cooke, “Learning each other’s ropes,” CBE-LSE 12 (Summer2013) 175-186