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RESEARCH www.rsc.org/cerp | Chemistry Education Research and Practice

A hurdle too high? Students’ experience of a PBL laboratory module

Orla Kellya

and Odilla Finlaysonb

Received 23rd June 2008, Accepted 26th November 2008

DOI: 10.1039/b901459b

The experience of a cohort of students enrolled in a Year 1 chemistry laboratory module deliveredthrough a problem-based learning approach was studied. The methodology involved both

qualitative and quantitative data analysis. The results show that students had a very positive

attitude toward the PBL approach.The data suggests that a high proportion of students felt that

learning and enjoyment in the PBL laboratory were better than in the traditional laboratory.

Furthermore, by the end of the module, 83% of students indicated a preference for the PBL

approach, and a similar percentage indicated they would choose to continue this alternative

approach into their second year. The study also suggests that those who have little background in

chemistry struggle more with the alternative approach at first, but over time the difference is

reduced. Ability to do calculations is found to be a significant factor in whether students prefer the

traditional or PBL approach.

Keywords: Problem-based learning, first year/general chemistry, laboratory work, previous chemistry experience

Introduction

Problem-based learning is an approach to curriculum/module

design that involves students engaging with problems from

practice, which provide a stimulus for learning. According to

Engel (1997 p. 15) “It is a means of developing learning for

capability rather than for the sake of acquiring knowledge”. It

is a student-centred approach, with the tutor as the facilitator.

In this role, the tutor shares the learning process with the

students, placing less emphasis on academic expertise and

more on the tutor’s ability to guide small group discussion and

decision making. This can be a threat to those who vieweducation as hierarchical. (Margetson 1997)

A problem-based learning (PBL) chemistry laboratory

module was developed and implemented over the course of

three academic years. The development of this module has

been previously described, (Kelly and Finlayson, 2007). The

aim of the module was to develop the students’ practical and

transferable skills, as well as their content knowledge and

scientific understanding, in an environment where there is

concern over the effectiveness of the traditional laboratory

courses. The rationale for evaluating the students’ experience

was three-fold: firstly, to allow for the ongoing development

and improvement of the module; secondly, to explore the

students’ experience of this alternative teaching and learningenvironment in terms of learning and enjoyment; and thirdly,

to investigate whether the experience of the module was

different for those students who had previous chemistry

experience compared with those who had not. In this paper the

second and final points will be considered.

Traditional vs. problem-based learning in the laboratory

Before investigating the experience of students taking this

problem-based approach, it is important to describe clearly

what the authors mean by a ‘traditional’ laboratory approach

and by a ‘problem-based’ one. The traditional laboratory

approach discussed in this study is similar to what other

authors have described as expository (Domin, 1999 and

Johnstone and Al-Shuaili, 2001). This means that the

procedure is given, the outcome predetermined and a

deductive approach is followed, whereby the students have

met the concept/theory/principle previously and are following

a procedure to evoke/prove this principle. However, it is

argued that this places little emphasis on thinking. Criticisms

of this approach include:

“Its ‘cookbook’ nature emphasises the following of specific

procedures to collect data;

It gives no room for the planning of an experiment;

It is an ineffective means of building concepts;

It is unrealistic in its portrayal of scientific

experimentation.”

(Johnstone and Al-Shuaili, 2001 p. 46)

In terms of assessment, the conventional written laboratory

report is the common assessment tool. It is disputed, however,

that this method does not allow for assessment of all

laboratory objectives. (Johnstone and Al-Shuaili, 2001)

Despite these criticisms, the expository style approach still

remains in many laboratories because it can cater for a large

number of students with minimal involvement from the

instructor, at a low cost, and is time efficient. Furthermore, it

can support certain aims of laboratory teaching, such as

development of manipulative and data-gathering skills.

(Johnstone, 2001) However, Lagowski (1990 p. 541), nearly

20 years ago, described how “laboratory experiences – the

heart of any science – have been allowed to degenerate to rote

exercises designed to consume minimal resources whether

time, space, equipment, or personnel”. It is because of a

combination of these problems coupled with our personal

experiences that we decided to investigate an alternative

approach to laboratory teaching, PBL, which until recently

a Faculty of Education, University of Plymouth, Plymouth, UK; E-mail:

[email protected] b School of Chemical Sciences, Dublin City University, Dublin 9, Ireland.

E-mail: [email protected]

42 | Chem. Educ. Res. Pract., 2009, 10, 42–52 This journal is © The Royal Society of Chemistry 2009



has been primarily reserved for the health disciplines.

PBL was initially developed by the Faculty of Medicine at

McMaster University in Canada where pure PBL courses

started with problems rather than the exposition of

disciplinary knowledge, with students moving towards the

acquisition of knowledge and skills through a staged sequence

of problems presented in context together with associated

learning materials and support from tutors (Boud and Feletti,1997). Margetson (1997) has pointed out that this encourages

open-minded, reflective, critical and active learning, with

students and teachers coming together in a shared educational

process. In this research an adapted form of PBL is used.

The problem-based approach differs from the traditional

‘expository’ approach in that the procedure is student

generated. The students are given a problem for which they

must provide a solution. There are, typically, several routes to

follow to solve the problem. Furthermore, the students take on

these problems in small groups. Students engage with and

build on concepts they have previously met, supporting a

constructivist approach to learning by both learning from their

peers and constructing meaning for themselves.There has been much discussion on the importance of

effective preparation by students for science lectures and

laboratory sessions, (Johnstone et al., 1994, Sirhan et al.,

1999, Sirhan and Reid, 2001, Byers, 2002). This is most

apparent in a problem-based approach, where students can be

at a complete loss when they are unprepared. A student

entering a laboratory without some preparation is likely to

spend hours of fruitless activity resulting in frustration and

limited learning. This PBL laboratory approach implemented

an assessed pre-laboratory element, which typically involved

some element of research into the chemical concepts and/or

techniques involved, as well as planning a strategy to solve

the problem. The problem-based style also allowed for other

modes of assessment, which included written laboratory

reports and oral and poster presentations. Furthermore,

students’ individual participation in the laboratories and in

their groups also provided opportunities for assessment.

The problems covered a range of content areas, which

matched the learning objectives and curriculum of the original

module, and the problems had different underlying purposes

depending on what the main focus of the problem was; either

concept driven problems, skills development or

understanding. There was often overlap between these foci.

An illustrative example of a PBL problem is the ‘Old Wives

Tale’.

Problem:

Your grandmother has been suffering with indigestion and

heartburn for the last few weeks. She’s been taking baking

soda to relieve the pain. However, you are concerned that

this is just an Old Wives Tale and the baking soda really

has no relieving effect. Your job is to determine if baking

soda is as effective as commercially available antacid

tablets, e.g. Bisodol, as an antacid supplement.

The students are required, through their pre-lab, to discuss

the reaction that takes place in the stomach between these

‘antacids’ and the gastric juices, through a series of prescribed

Table 1 Summary of the differences between the two approaches adopted

in this study

Factor Traditional/Expository Problem-based

Pre-lab Read the manual Pre-lab task

Group size 2 2-4

Teacher role Demonstrator Facilitator

AssessmentWritten lab report

(100%)

Written pre and post labreports

Oral and poster

presentations

Group and individual

contributions to labs

Outcome Predetermined Predetermined

Approach Deductive Deductive

Procedure Gi env Student generated

guided questions. They are also asked to describe an

experiment, which would be suitable to solve this problem.

Students typically suggest titrimetric analysis to solve the

problem. However, few have met the concept of a back-titration before, and even if they do come across it during

their research they do not fully understand it. Therefore, the

pre-lab discussion is used to facilitate student understanding

of ‘back-titration’ and how it can be used for this experiment.

Students perform two sets of titrations during this problem –

one on baking soda and the other on an antacid. It is essential

that they set up the experiment in such a way that makes

comparison of their results possible. This gives them

experience in experimental design and the concept of controls

and variables. On successful completion of the practical task,

the students must then analyse their results in detail in order

to make appropriate conclusions. Since the result is unknown,

they are not expecting any particular result, thus making thewhole experience more authentic, and requiring real

engagement with their data. For further discussion on this

alternative approach, see Kelly and Finlayson (2007). See

Table 1 for a summary of the differences between the two

approaches discussed in this study.

Research on student experiences of PBL in the sciences

PBL started in the health disciplines, and today still provides

the bulk of literature on research into students’ experiences of

this approach. Recent studies, however, have looked at the

experiences of students undertaking a PBL approach in

scientific disciplines ranging from chemical engineering to

physics (Albanese and Mitchell, 1993; Belt et al., 2002;Chung and Chow, 1999; Savin-Baden, 2004; Tan, 2004,

TLRP, 2004 and Van Kampen et al., 2004). The extensive

study carried out by Albanese and Mitchell (1993) reported

that studies of students’ attitudes after taking PBL modules

uniformly showed high levels of satisfaction.

Tan (2004) described results from a study designed to

assess students’ experience of PBL, from a range of

disciplines, in terms of the ‘problem’, the ‘tutor’ and

‘problem-solving’. The study found that in general students

were positive about their experiences with PBL. The students

rated the ‘problem’, ‘problem solving’ and ‘coach’ (or

facilitator). The ‘problem’ and ‘problem solving’ had similar

This journal is © The Royal Society of Chemistry 2009 Chem. Educ. Res. Pract., 2009, 10, 42–52 | 43



means of 34.0 and 33.4 respectively (out of a maximum of

50), whereas the ‘coach’ had a lower mean of 25.5.

Van Kampen et al. (2004) reported on the student

experience of an Introductory Thermal Physics PBL Course,

designed for 2nd year students. Students reported that thermal

physics was significantly more interesting and relevant,

having completed the PBL course, with an increase from 3.0

and 2.7 in the pre-intervention survey to 3.9 and 4.1respectively in the post-intervention survey for each factor

(out of a maximum of 5). Furthermore, student attendance

also rose to almost 100%. The only negative aspect noted was

the amount of time required. The students involved in ‘The

Pale Horse’ case study (Belt et al., 2002), a PBL approach to

analytical and applied chemistry, were asked to rate their

enjoyment of taking part in the activity on a 5-point Likert

scale. A mean response of 4.3 (n = 45) indicated a highly

positive experience. A similar study by Heaton et al. (2006)

showed a mean response of 4.2 out of 5 for a PBL case study

in green chemistry.

Savin-Baden (2004) reported on students’ experience of the

assessment process in PBL. The study involved four universities over 5 years, with students from 3 rd year of

mechanical engineering, 2nd and 4th years of auto design

engineering courses, 2nd year nursing and from a diploma

course in social work. Students reported that their learning

was unrewarded, that they felt disempowered by complex

assessment mechanisms, and that working in groups was

undervalued. These studies helped toward devising a research

method, which would allow for some comparison across the

literature.

Method

Summary of surveys

Students were asked to complete three surveys over the course

of the year-long PBL module: a survey at the end of semester

1 (A) (see Appendix 1a), a similar survey at the end of

semester 2 (B) and another survey (C) which they completed

after they had done a traditional laboratory chemistry practical

(see Appendix 1b). These surveys gave rise to both

quantitative and qualitative data. Table 2 gives a summary of

the number of students who completed each survey. This

generally represented an 85-90% response rate. Non-

parametric tests were used to analyse the Likert scale data.

Semi-structured interviews

Semi-structured small group interviews were also conducted

with ten students from the PBL cohort from 2003-2004. The

students selected were representative of the PBL group in

terms of gender, academic achievement to date in the module

and previous chemistry experience. The interviews were

conducted by people not otherwise part of the research study,

using a series of focussed questions to which the students

were asked to respond, (See Appendix 2). The interviewer

encouraged the students to extend and elaborate on their

answers, to provide a richer picture of their experiences. The

interviews were held at the end of the second semester, and

reflected on the year-long PBL module for the students who

Table 2 Summary of the number of students who completed each survey

Academic Year Survey Code Response

02-03* 03-04 04-05

End of semester 1 A 48 (66 incl. 02-03) Y Y Y

End of semester 2 B 43 N Y Y

Traditional vs. PBL C 42 N Y Y

Interviews 10out of 26 studentsselected

N Y N

* Note: The PBL module was only run in the first semester in this

academic year

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

Fun Learning

experience

Understanding Competency in

techniques

Calc ulat ions Tac kl ing

problems

M e a n r a t i n g ( s c a l e o f 1 t o 5 )

End of Semester 1

End of Semester 2

Fig. 1 Mean rating for each factor at the end of semester 1 and end of

semester 2.

followed it. The results from the interviews are discussed

throughout this paper to support findings from the survey

data.

Results

Overview of the experience of the students

Similarly to the other research studies mentioned earlier, the

students rated their experience of the alternative approach to

their laboratory module. We focussed on the following

elements:

• Fun

• Learning experience

• Understanding

• Competency in techniques

• Calculations

• Tackling problems

This was to reflect the aims and objectives of the

alternative approach. The students rated their experience of or

confidence in each of these factors on a scale of 1 to 5, with 1

being a very negative experience, or little confidence and 5

being a very positive one or a lot of confidence. Figure 1

shows the ratings for each factor at the end of both semesters.

Fig. 1 shows that the students rated ‘fun’ and ‘competency

in techniques’ most positively. Calculations were the factor

they rated lowest. Statistical tests revealed that there were no

significant differences between the ratings at the ends of

semester 1 and 2. (See Appendix 3 – Table A1) The students

were also asked to indicate their most liked and disliked

elements, as well as the most and least beneficial aspects of

the PBL approach in their view. An analysis of




Table 3 The most and least beneficial aspect for each semester

End of semester Most beneficial aspect Least beneficial aspect

1 Pre-lab Poster presentations

2 Pre-lab Specific experiments

Table 4 The top three likes and dislikes for each semester

End of

semester

Likes Dislikes

1st Group work Calculations

2nd Hands-on experiments Pre-lab1

3rd Laboratory

environment

Write-ups (and time spent

on them)

1st Group work Pre-lab

2nd Laboratory

environment

Write-ups2

3rd PBL approach Calculations

their responses gives further insight into the students’

experiences. Table 3 shows the most frequently cited aspects

as ‘most’ and ‘least’ beneficial for both semesters. Table 4

shows the top three most frequently cited likes and dislikes

for both semesters. Other beneficial aspects commonly listed

by the students included group work, discussion, sense of

ownership/responsibility and doing practical work.

Table 3 shows that the pre-lab was seen as the most

beneficial aspect of the alternative approach, and yet it also

features for both semesters in dislikes (Table 4). This was a

feature throughout the study; the students recognising and

appreciating the learning that came from the pre-labs, but also

often frustrated by individual ones or the small contribution

their time and effort made towards the final mark. Evidence

from the interviews supports this.

Interviewer C: What aspects of the laboratory did you dislike?

Student A: Maybe the pre lab. I thought that was a good

thing, so I’m contradicting myself.

Student B: I know what you mean but there were aspects of

pre lab that bothered me as well even though I think it’s a

good idea.

Specific reasons given for disliking the pre-lab included

difficulty in accessing information for some experiments, and

frustration when time spent on this was not reflected in the

mark they received. In terms of the least beneficial aspects,

one of the poster activities (where all the students presented a

poster on the same topic) and certain individual experiments

were cited most frequently in terms 1 and 2 respectively.

The students really liked the group work, which emerged as

the most liked aspect in both semesters over the course of the

study. They also liked the relaxed and friendly lab

environment, as well as the actual hands-on nature of the

experiments and the PBL approach. Conversely, they disliked

the calculations, certain pre-labs and the laboratory write-ups.

The latter was particularly an issue in term 1, where the

students who followed the traditional approach completed

their laboratory write-up during the lab time, unlike the

students following the PBL approach. Combining the time

Fig. 2 Proportion of students who indicated a preference for the problem-

based approach over a traditional approach to chemistry laboratories.

spent on the pre-lab plus the time spent completing the write-

up meant the PBL students were spending more time outside

of the lab session on their chemistry than their traditional

counterparts.

Preference for PBL

One factor that was consistently monitored throughout the

study was the students’ preference for either the traditional or the PBL approach to chemistry laboratories. And in one of the

surveys, students were also asked to indicate if “given a

choice would they continue to follow a PBL approach into

2nd year?”. This was not an option for the cohorts

undertaking the module at the time, but is something that the

programme director was considering. This was relayed to the

students before completing the survey. Additionally, the

students’ previous experience in chemistry was also

monitored (academic years 2003-2004, 2004-2005 only).

From Fig. 2 it is clear that students indicated a preference

for the PBL approach. However, there is a difference in

preference for the PBL approach between those who had and

had not done chemistry before, when they were questioned atthe end of their first semester of the problem-based approach.

A higher percentage of students who had studied chemistry

before indicated a preference for PBL, 67%, compared to 47%

of students who had no previous chemistry experience. It is

worth commenting that all the students were undertaking a

laboratory module in physics as part of their degree

programme at the same time, which was delivered through a

traditional approach. Furthermore, all students would have

undertaken at least one science subject for their Leaving

Certificate (state examination taken in the final year of

secondary school in Ireland) where they would have

experienced laboratory work in a traditional style. Therefore,

though some students may not have experienced traditionalchemistry laboratory work before, all students would be

familiar with, and have experienced the traditional approach

to laboratory work in one or other of the science subjects, thus

asking them their preference between the two approaches is a

useful and valid question.

An interesting finding is that their preference increases

over time; while 60% indicated a preference for PBL at the

end of semester 1, an increase to 83% is reported at the end of

semester 2 for the same group. This is consistent with the

results from survey C, where 86% indicated a preference for

PBL, and 83% indicated they would choose to follow it into




Table 5 Comparison of the mean rank for each significant factor against

students’ preference for approach

Student preferenceFactor

PBL Trad.

End of Semester 1 Mean Rank U p

Understanding 29.50 17.50 140.000 0.002

Calculations 30.86 15.60 102.000 0.000End of Semester 2 Mean rank U p

Fun 18.91 9.30 31.500 0.033

Learning experience 23.54 11.29 51.000 0.006

Calculations 23.84 9.79 40.500 0.005

year 2. This survey was carried out after the students had

completed a chemistry experiment following the traditional

approach (see Appendix 1b). Furthermore, by the end of the

second semester there was no difference in the preference

between those with or without a background in chemistry.

Students were asked to rate their experience of, or

confidence in a number of factors on a 5-point scale. These

were – fun, learning experience, understanding, competency

in techniques, calculations, and tackling problems (see

Appendix 1a). The Mann-Whitney U-test was used to

determine if there were any significant differences between

the ratings of these factors, with the students’ preference for

either the traditional or PBL approach as the variable. Table 5

shows the factors where the scores were significantly different

from those who indicated a preference for the PBL approach

compared with those who indicated a preference for the

traditional approach at the end of both semester 1 and 2. Note,

these students were all following the PBL approach.

At the end of semester 1 the results show that the mean

ratings for ‘Fun’, ‘Learning experience’ and ‘Competency in

techniques’ and ‘Tackling problems’ were no different for

those participants who showed a preference for the PBL than

for those who showed a preference for the traditional

approach. In contrast, the mean ratings for ‘Understanding’

and ‘Calculations’ were significantly higher for those

participants who showed a preference for the PBL than for

those who showed a preference for the traditional approach.

(See Appendix Table A2-3 for all data) This showed that

students who indicated a preference for the PBL approach felt

they understood more and were better able to do their

calculations than those who indicated a preference for a

traditional approach.

At the end of semester 2, a similar study was carried out.

The results showed that, overall, those who indicated a

preference for a PBL approach rated their experience of

laboratories in terms of ‘fun’, ‘learning experience’ and

‘calculations’ higher than their peers who indicated a

preference for the traditional approach. It is worth

commenting that the ability to do calculations was a

significant factor for both semesters for those who preferred

the PBL approach.

In survey C, their preferences were further examined. The

students completed this survey after completing a traditional

chemistry laboratory practical and so had just experienced

first-hand the traditional laboratory approach. (See Appendix

Table 6 Summary of the breakdown of the students’ preference in terms

of four distinct factors

% of studentsPreference in terms of

PBL Traditional No preference

Enjoyment of the lab 90 5 5

Learning in the lab 95 2.5 2.5

Which lab was easier 63 34 3Lab write-up 53 39 8

1b for details) Furthermore, the same tutor who delivered the

PBL module also delivered this traditional laboratory. Table 6

summarises the results. It can be seen that 95% and 90% of

the students indicated that for learning and enjoyment in the

laboratory they favoured the PBL approach. Explanations for

preferring the PBL approach, in terms of learning, included:

“The PBL approach, because (again) we usually had to

look up the procedure before we came into the lab so

therefore the experiments stuck in my head.”

“You get to relate it to life and what way the chemistry of the experiment relates to the world we live in.”

“By working out the procedure you understood exactly

what you were doing.”

Some of the reasons given for students enjoying the PBL

laboratory more included:

“Learned more, as with the traditional you’re given the

procedure don’t have to really think about what you’re

doing.”

“When we had to present our results it was a bit of

competition, good fun, also made us be more accurate.’

‘Because it made you think and it sometimes was a

challenge. I like challenges.”

“Gave the chance to learn why we were doing anexperiment and research background to it. This allowed a

proper understanding of the procedure rather than just

following the manual.”

In contrast, reasons cited for enjoying the traditional

laboratories more include:

“Because didn’t have to worry about pre-labs and lab

reports outside lab times.”

“The traditional lab was more enjoyable because I knew

what I was doing during the lab.”

In terms of students’ judgement on which laboratory was

easier, Table 6 shows that 63% of the students favoured PBL.

Here are some of the explanations students gave for their

choice:“I didn’t know exactly what was happening in the

traditional experiment, I was just following the procedure.”

“Because it was easier to understand what we were doing.”

“I just felt that the PBL made you think about what you

were doing.”

In comparison, students gave the following explanations for

indicating that the traditional laboratories were easier:

“Procedure laid out – didn’t need to think a lot.”

“Because you are given a step by step method of how to

conduct the experiment.”

“Less work!”

The group was divided on the final question ‘Which write-




up was easier to do?’ with 39% of students indicating that the

traditional laboratory report was easier to do. Some of the

reasons given for this included:

“You could just copy straight from the lab manual.”

“Traditional lab is easier to do, but not of as much

benefit.”

When following the traditional approach, students were

always given the procedure and usually a worked example of how to complete their calculations. In semester 1, the students

also got to complete this during lab time. However, when

following the PBL approach, the write-up was always

completed outside of the lab time and typically the students

neither had a direct method to follow, nor a worked example.

The style of the write-ups were quite similar, regardless of

whether is was a traditional or PBL laboratory, except that the

PBL laboratory would require an informative conclusion

relating the results of the experiment to the original problem.

This may account for why a good percentage of students felt

the traditional laboratory was easier.

There seems to be a recurring theme where students

recognise the benefits that come from engagement at a higher cognitive level, with particular aspects of the approach e.g.

pre-lab, planning their own approach, write-up, but dislike it

because it ultimately means more and harder work.

The importance of a background in chemistry

Further analysis of the data from surveys A and B on the

students’ rating of various factors, showed there was a

significant difference between the ratings for some of the six

factors between those students who had studied chemistry

before and those who had not. The mean ratings for ‘Fun’,

‘Learning experience’ and ‘Competency in techniques’ were

much the same for those participants who had studied

chemistry before as for those who had not studied chemistry before. However, ‘understanding’, ‘ability to do calculations’

and ‘tackling problems’ were identified as factors which those

who have studied chemistry before rated higher than those

who hadn’t. (See Appendix 3 Table A4 for all data and Table

7 for significant data) This suggests that those who had a

background in chemistry felt they understood more, were

more able to do calculations and were more competent in

tackling problems. Further analysis reveals that of those who

have studied chemistry before, those who indicated a

preference for PBL rated only ‘Calculations’ significantly

higher than those who indicated the traditional approach.

Also, on analysis of those students with no background in

chemistry, ‘Understanding’ and ‘Competency in techniques’

were revealed as the areas, which those who indicated a

preference for PBL rated significantly higher than those with

a preference for the traditional approach. (See Appendix 3

Tables A5 and A6)

At the end of the second semester a similar analysis was

done. This time ‘understanding’, ‘competency in techniques’,

‘ability to do calculations’ and ‘tackling problems’ were all

identified as factors that those who had studied chemistry

before rated higher than those who hadn’t. (See Appendix 3

Table A7 for all data and Table 7 above for significant data)

This is worrying, as it suggests that the gap between those

Table 7 The mean scores for each significant factor related to students’

background in chemistry

Chemistry backgroundFactor/Mean score

yes no

End of Semester 1 Mean rank U p

Understanding 27.45 17.31 141.000 0.011

Calculations 28.73 14.84 101.500 0.001Tackling problems 28.05 16.16 122.500 0.003

End of Semester 2 Mean rank U p

Understanding 27.12 14.18 88.000 0.000

Calculations 25.88 16.06 120.000 0.010

Tackling problems 25.38 16.82 133.000 0.021

These factors are ranked significantly higher for the students with a

chemistry background, with p ≤ 0.05.

who had and those who hadn’t studied chemistry before has,

in fact, widened over the course of this introductory module.

Further analysis revealed that those who have studied

chemistry and who indicated a preference for PBL rated

‘Learning experience’ and ‘Calculations’ significantly higher

than those who indicated the traditional approach.Interestingly, on analysis of the non-chemistry group, the

Mann-Whitney test showed no significant difference between

any of the factors for those who indicated a preference for

PBL and those who indicated the traditional approach. (See

Appendix 3 Tables A8 and A9)

Discussion and implications for teaching

This study showed that students generally had a very positive

attitude toward the PBL approach. This is consistent with

findings in other studies such as the large scale Albanese and

Mitchell study (1993) and more recent specific studies in

science (Belt et al., 2002; Van Kampen et al., 2004). It is alsoclear though that students’ contrasting experiences with PBL,

as described in other research, are also found here.

Additionally, the data shows that 95% of the students

following the PBL approach felt they learnt more than in the

traditional laboratories, and 90% enjoyed it more. However, it

is worth asking if their perceived increased learning is due to

just spending more time on their chemistry or is it to do with

the nature of the time spent on the laboratories? For example

the time spent on the pre-lab, working through the problems in

groups, discussing the chemistry with the facilitator in a

friendly and relaxed environment? The data would suggest

this is so.

Group work has been reported as a negative aspect of PBLin one study (Tan, 2004), however our study found mostly

positive experiences of working in groups, with students

citing it as the feature they liked most about the approach,and

more importantly, noted as a beneficial aspect of the

laboratories (see Table 4). A small number commented on

particular difficulties with individuals in their groups;

however, this is not unique to PBL.

Furthermore, the relaxed and friendly environment came

out as one of the top three ‘likes’ in both semesters. It is

suggested that this is in part due to the role adopted by the

tutor and in part due to the nature of the PBL laboratories. The

tutor was adopting the typical tutor role in PBL, that of a




facilitator rather than the laboratory demonstrator/tutor who

typically plays the role of knowledge expert. In a separate

study (Kelly and Cutting, 2008, p. 949), students reported

positively on the changing role of the tutor, despite the

concerns of the tutor “It made me feel more relaxed…it made

me feel like you’re a person – you’re not some sort of like

godly knowall creature”

The effect of the pre-lab on student learning should also beconsidered. Tan (2004) reported the students’ frustration with

the problems, but also that students found the problems very

motivating. This mirrors our results in terms of students’

frustrations and dislike of pre-labs, whilst conversely

reporting pre-labs as one of the most beneficial aspects. Tan

(2004) also reported that students often felt they needed more

pointers or help. It is proposed that this was one of the main

sources of the students’ frustration with pre-labs in this study.

It was evident that students felt they were ‘wasting time’

trying to find useful resources to solve the problems, or felt

they lacked the background to make good use of their time.

Subsequently, over the duration of the study, the resources

and help available to the students were tailored to make better use of their time spent outside of the laboratories. The

implication for teaching is that pre-labs are a very beneficial

component of laboratory work, but with Year 1 undergraduate

students this needs to be guided with suggested reading and/or

web links to save them fruitless searching.

Time, in terms of students feeling they had to spend more

time on their chemistry laboratories than their ‘traditional’

counterparts, was another issue which may have added to their

frustrations. This was similar to the results found in the study

carried out by Van Kampen et al. (2004) on PBL in physics,

where the only negative aspect mentioned was the amount of

time it required.

‘Ability to do calculations’ was the factor where students

rated themselves lowest at the end of both semesters.

Furthermore, their ‘Ability to do calculations’ was the only

factor rated significantly lower by students’ who indicated a

preference for the traditional approach in both semesters,

irrespective of whether or not they had studied chemistry

before. This suggests that students recognise the importance

of success in calculations. It is particularly relevant in the

PBL approach, as students need to relate their findings to the

initial problem, so if they are unsuccessful at that point they

will be unable to write a meaningful conclusion.

“The conclusion takes time to do at the end and even

though calculations are pretty difficult, trying to think of

something to write for a conclusion is harder because you

basically have had to understood what you did” Student D

In the traditional approach the students are guided through

each calculation step-by-step in their laboratory manual, and

for the most part, all that is required is for the numbers to be

changed, using the results they obtained in their experiment.

Additionally, the conclusion usually consists of merely stating

the result. It could be argued that this is necessary as the

chemistry laboratory and lecture course do not run

sequentially and so students are not getting the theoretical

support at the right time. However, it could also be argued

that they are learning only to ‘number crunch’. Although the

students following the PBL approach may struggle initially

with it, usually by the end they have learned how to tackle the

calculations themselves.

“For someone that hadn’t done chemistry I had no

background for how to work it out. Now that I’ve done half

a year this semester is grand.” Student E

Other data supports this assertion, since the preference for

the PBL approach increases from 47% to 82.5% over thecourse of the module for those without a background in

chemistry. The implications for teaching are that tutors need

to scaffold students learning carefully in ‘calculations’

through a series of problems in context with increasing

difficulty so as to minimise students frustration and maximise

their learning.

Assessment in PBL was reported as one of the significant

issues for students (Savin-Baden, 2004), particularly in terms

of unrewarded learning, undervalued group work and complex

assessment mechanisms. The main issue in this study was

students feeling time spent on the pre-lab was not adequately

rewarded in terms of assessment. This has subsequently been

addressed by making the assessment requirements moretransparent to students.

One of the aims of the study was to determine if the

experience was the same for students with different

backgrounds in chemistry. We saw that despite a difference in

preference for the PBL approach at the end of semester 1

between those who had and had not done chemistry before,

there was no such difference by the end of the second

semester. This suggests that those who have little background

in chemistry struggle more with the alternative approach at

first, but over time the difference is reduced.

Unsurprisingly, students who have studied chemistry before

rate their ability in a number of the factors significantly higher

than their counterparts who have not studied chemistry,

including understanding and ability to do calculations. Most

notably, ‘tackling problems’ was rated significantly higher at

the end of both semesters 1 and 2 by those who have studied

chemistry before. This reflects a higher confidence in this

scientific process skills. Does this suggest that students who

have studied other science subjects in school have had less

opportunity to develop this skill, or does it suggest that it is

not developed as a transferable skill which is independent of

the subject discipline? It would be interesting also to consider

these factors for the students who followed the traditional

approach to allow for comparison to see if the findings are

similar. The implications of this are two-fold; firstly, we need

to monitor closely modules that act as introductions to subject

knowledge and skills designed to bring everyone to a common

level, as is the case in this module, and ensure that these

objectives are being met. Traditional laboratory assessments,

such as write-ups, may not allow gaps in understanding to be

identified. Alternative laboratory assessments must be

considered. Secondly, we need to be aware of the skills that

students bring from their prior experiences. Tackling new

content, as well as new techniques in a challenging

environment demanding creative problem-solving may well be

a hurdle too high, thus severely limiting any chance of

learning.




Conclusion

This study aimed to evaluate students’ experience of a PBL

module in chemistry. The evaluation allowed for exploration

of the student’s experience of the alternative teaching and

learning approach to chemistry laboratories in terms of

learning and enjoyment. It was shown that a high proportion

of students felt that learning and enjoyment in the PBLlaboratory were better than in the traditional laboratory.

Furthermore, by the end of the module 83% of students

indicated a preference for the PBL approach, and a similar

percentage indicated they would choose to continue this

alternative approach into their second year. In addition, the

students’ attitude towards the laboratory, as demonstrated by

their preference for the approach, increased over the duration

of the module. The evidence suggests a genuine effectiveness

of progressive teaching appproaches. Often students’ do not

like change or new challenges, and we could easily have give

up without seeing it through.

The other aim of the evaluation was to investigate whether

the experience of the module was different for those studentswho had previous chemistry experience from those who had

not. It was shown that after a semester those with chemistry

indicated more of a preference for the PBL approach,

however, after a year of the module, the near-same percentage

of ‘chemists’ and ‘non-chemists’ indicated a preference for

the PBL approach (83% and 82.5% respectively). Competence

at calculations was a consistent factor for the ‘chemists’, since

at the end of both semesters 1 and 2, the ‘chemists’ who

indicated a preference for the PBL approach rated it

significantly higher than their fellow ‘chemists’, who

indicated a preference for the traditional approach. The results

for the non-chemists were not as clear- cut. ‘Understanding’

and ‘competency in techniques’ were rated significantlyhigher at the end of semester 1 by the non-chemists who

indicated a preference for the PBL approach than their fellow

non-chemists, who indicated a preference for the traditional

approach. In contrast, no differences were observed at the end

of the 2nd semester.

Despite some evidence on the effect of chemistry

experience on students’ experience of PBL, it is felt that this

is at a preliminary stage only, and that more investigation is

needed. Further research questions identified in this area

include investigating the strategy/approach to the problems

taken by the ‘chemists’ and ‘non-chemists’, and investigating

the correlation between their experience of the PBL and their

approach to learning.To conclude, the PBL approach is seen as a success, since

the majority of students would choose to follow it into the

next year, despite its various drawbacks. Furthermore, despite

some initial differences in the experiences of those with

different backgrounds in chemistry, these seem to become less

of a problem the more familiar the students become with the

approach and chemistry content and context.

Appendixes

Appendix 1a – End of Semester 1/2 Survey (Survey A/B)

Please complete this survey regarding the Problem Based

Learning chemistry labs, thanks.

What do you feel was the most beneficial aspect of the labs? ________________________________________________

What do you think was the least beneficial aspect of the labs?

_________________________________________________

Describe three things you liked about the labs?

________________________________________________

________________________________________________

________________________________________________

Describe three things you disliked about the labs?

_________________________________________________

_________________________________________________

_________________________________________________

Rate your experience of 1st year Chemistry labs in relation to

each of the following:

Fun 1 – Notenjoyable 2 3 4 5 – Very enjoyable

Learning

experience

1 – Learned

nothing2 3 4

5- Learned

everything

Understanding1 – Understood

nothing2 3 4

5 – Understood

everything

Competencyin techniques

1 - Incompetent 2 3 45 – Extremelycompetent

Calculations1 – Haven’t aclue

2 3 45 – Can do and getright

Tackling problems

1 – Haven’t aclue

2 3 4

5 – Sensible,

researched,

approach

Please tick box for preference for- traditional approach - problem-based approach

Have you studied chemistry before? Yes No

What changes could be made regarding how they areadministered? ____________________________________________________

Any other suggestions/comments: ___________________________________________________

Appendix 1b – Traditional versus Problem Based LearningSurvey (Survey C)

Traditional versus Problem Based Learning – your verdict

Last week, you did an experiment titled ‘Dehydration of 4-

Methylpentan-2-ol and Isolation of the Products by

Distillation’. This was the only lab done in the traditional

way, i.e. you were not given any prior instructions before

entering the lab, and followed a set procedure and did your

write-up accordingly.

All the other weeks you have tackled experiments using a

problem based (PBL) approach. The following questions are

set to gauge any differences in the two methods from your

point of view.

Thanks for taking the time to complete the survey.




1. Did you spend time preparing for the traditional lab?

Yes NoIf so, how long? _________________

2. Normally did you spend time preparing for the PBL labs?

Yes No

If so, how long? _________________

3. If you prepared for both the traditional and PBL labs, which

preparation did you feel was the more beneficial?

Trad PBL

Why? __________________________________________

1. Experimentally, which labs did you find easier to do?

Trad PBLWhy?

________________________________________________

2. Which lab did you enjoy more? Trad PBL

Why? ________________________________________________

3. Which lab did you feel you learned more from?

Trad PBL

Why? ___________________________________________

4. Which write-up was easier to do? Trad PBLWhy?

_____________________________________________

5. If given a choice, which approach would you choose to do?

Trad PB

L6. If given a choice, which approach would you choose to do in

2nd year? Trad PBL

Appendix 2 – Interview schedule

1. Have you done Leaving Certificate Chemistry? Or studiedchemistry previous to starting this academic year?

2. Did you enjoy chemistry labs? Why? Why not?3. What experiment(s) do you remember from the 1st semester?

Why?a. Purpose/Result

4. What experiment(s) do you remember from the 2nd semester?Why?

a. Purpose/Result5. What aspects of the labs did you dislike?

6. Before coming into the lab, in general did you know what theaim of the experiment was?

7. How much time did you spend on pre-lab exercise? Did youuse the literature resources liste?

8. Was this useful for the lab itself?9. Did you learn anything in doing write-ups?10. How much time did it take?

11. Did you read marks/feedback? Did you change as a result of this?

12. Are titrations a useful technique?

Appendix 3: Mann-Whitney U-Test data

Table A1 Table showing results of comparison of responses between end

of semester 1 and 2

Ranks

Factor Survey N

MeanRank

Sum of Ranks

U p

End of sem 1 43 38.43 1652.5Fun

End of sem 2 35 40.81 1428.5706.5 0.623

End of sem 1 48 47.92 2300Learning

experience End of sem 2 43 43.86 1886940 0.408

End of sem 1 48 47.64 2286.5Understanding

End of sem 2 43 44.17 1899.5953.5 0.500

End of sem 1 46 45.93 2113Competency in

techniques End of sem 2 43 44 1892946 0.701

End of sem 1 48 48.01 2304.5Calculations

End of sem 2 43 43.76 1881.5935.5 0.431

End of sem 1 48 44.85 2153Tackling

problems End of sem 2 43 47.28 2033977 0.643

Table A2 Table showing results of comparison of responses between

those who preferred the traditional approach compared to the PBL

approach in semester 1

Semester 1 Ranks

Factor Preference for NMeanRank

Sum of Ranks

U p

Traditional 19 18.76 356.5Fun

PBL 24 24.56 589.5166.5 0.111

Traditional 20 23.1 462Learning

experience PBL 28 25.5 714252 0.514

Traditional 20 17.5 350Understanding

PBL 28 29.5 826140 0.002

Traditional 19 20.24 384.5Competency intechniques PBL 27 25.8 696.5 194.5 0.130

Traditional 20 15.6 312Calculations

PBL 28 30.86 864102 0.000

Traditional 20 20.72 414.5Tackling

problems PBL 28 27.2 761.5204.5 0.091



approach in semester 2

Semester 2 Ranks


Sum of Ranks

U p


PBL 29 18.91 548.531.5 0.033

Traditional 7 11.29 79Learning

experience PBL 35 23.54 82451 0.006


PBL 35 22.57 79085 0.164

Traditional 7 17.57 123Competency in

techniques PBL 35 22.29 78095 0.313

Traditional 7 9.79 68.5Calculations

PBL 35 23.84 834.540.5 0.005


problems PBL 35 22.61 791.583.5 0.166





those who had previous chemistry experience and those who had no

previous chemistry experience in semester 1

Semester 1 Ranks

Factor

Previous

chemistry

experience NMean

Rank

Sum of

Ranks

U p

Yes 30 22.2 666Fun

No 12 19.75 237159 0.536

Yes 31 24.4 756.5Learning

experience No 16 23.22 371.5235.5 0.753

Yes 31 27.45 851Understanding

No 16 17.31 277141 0.011

Yes 30 25.3 759Competency in

techniques No 15 18.4 276156 0.070

Yes 31 28.73 890.5Calculations

No 16 14.84 237.5101.5 0.001

Yes 31 28.05 869.5Tackling

problems No 16 16.16 258.5122.5 0.003



approach in semester 1 for those who had previous chemistry experience

Semester 1, Previous

chemistry experience

Ranks

Factor Preference for NMean

Rank

Sum of

Ranks

U p


PBL 20 16.42 328.581.5 0.391

Traditional 10 17.05 170.5Learning

experience PBL 21 15.5 325.594.5 0.620


PBL 21 17.67 37170 0.109

Traditional 9 15.61 140.5Competency in

techniques PBL 21 15.45 324.593.5 0.960


PBL 21 19.45 408.532.5 0.001

Traditional 10 13 130Tackling

problems PBL 21 17.43 36675 0.173



approach in semester 1 for those who had no previous chemistry

experience

Semester 1, No previous


Ranks


Sum of Ranks

U p

Traditional 8 5.62 45

Fun PBL 4 8.25 33 9 0.194Traditional 9 7.33 66Learning

experience PBL 7 10 7021 0.212

Traditional 9 6 54Understanding

PBL 7 11.71 829 0.008


techniques PBL 6 10.58 63.511.5 0.046

Traditional 9 7.11 64Calculations

PBL 7 10.29 7219 0.166

Traditional 9 8.67 78Tackling

problems PBL 7 8.29 5830 0.863


those who had previous chemistry experience and those who had no

previous chemistry experience in semester 2

Semester 2 Ranks

Factor

Previous

chemistry

experience NMean

Rank

Sum of

Ranks

U p

Yes 22 20.36 448Fun

No 13 14 182

91 0.057

Yes 26 21.69 564Learning

experience No 17 22.47 382213 0.819

Yes 26 27.12 705Understanding

No 17 14.18 24188 0.000

Yes 26 24.77 644Competency in

techniques No 17 17.76 302149 0.053

Yes 26 25.88 673Calculations

No 17 16.06 273120 0.010

Yes 26 25.38 660Tackling

problems No 17 16.82 286133 0.021

Table A8 – Table showing results of comparison of responses between


approach in semester 2 for those who had previous chemistry experience

Semester 2, Previous


Ranks

Factor Preference for NMean

Rank

Sum of

Ranks

U p


PBL 19 11.61 220.57.5 0.134

Traditional 4 5 20Learning

experience PBL 21 14.52 30510 0.007

Traditional 4 9.62 38.5Understanding

PBL 21 13.64 286.528.5 0.202

Traditional 4 10.5 42Competency in

techniques PBL 21 13.48 28332 0.398


PBL 21 14.55 305.59.5 0.013

Traditional 4 7.5 30Tackling

problems PBL 21 14.05 29520 0.085



approach in semester 2 for those who had no previous chemistry

experience

Semester 2, No previous


Ranks


Sum of Ranks

U p

Traditional 3 4.67 14Fun

PBL 10 7.7 778 0.209

Traditional 3 6.83 20.5Learning

experience PBL 14 9.46 132.514.5 0.338


PBL 14 9.29 13017 0.579


techniques PBL 14 9.18 128.518.5 0.738

Traditional 3 5 15Calculations

PBL 14 9.86 1389 0.116


problems PBL 14 9.04 126.520.5 0.947




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