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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]
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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
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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
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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
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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-
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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
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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.
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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.
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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
Table A3 Table showing results of comparison of responses between
those who preferred the traditional approach compared to the PBL
approach in semester 2
Semester 2 Ranks
Factor Preference for NMeanRank
Sum of Ranks
U p
Traditional 5 9.3 46.5Fun
PBL 29 18.91 548.531.5 0.033
Traditional 7 11.29 79Learning
experience PBL 35 23.54 82451 0.006
Traditional 7 16.14 113Understanding
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
Traditional 7 15.93 111.5Tackling
problems PBL 35 22.61 791.583.5 0.166
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Table A4 Table showing results of comparison of responses between
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
Table A5 Table showing results of comparison of responses between
those who preferred the traditional approach compared to the PBL
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
Traditional 10 13.65 136.5Fun
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
Traditional 10 12.5 125Understanding
PBL 21 17.67 37170 0.109
Traditional 9 15.61 140.5Competency in
techniques PBL 21 15.45 324.593.5 0.960
Traditional 10 8.75 87.5Calculations
PBL 21 19.45 408.532.5 0.001
Traditional 10 13 130Tackling
problems PBL 21 17.43 36675 0.173
Table A6 Table showing results of comparison of responses between
those who preferred the traditional approach compared to the PBL
approach in semester 1 for those who had no previous chemistry
experience
Semester 1, No previous
chemistry experience
Ranks
Factor Preference for NMeanRank
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
Traditional 9 6.28 56.5Competency in
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
Table A7 Table showing results of comparison of responses between
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
those who preferred the traditional approach compared to the PBL
approach in semester 2 for those who had previous chemistry experience
Semester 2, Previous
chemistry experience
Ranks
Factor Preference for NMean
Rank
Sum of
Ranks
U p
Traditional 2 5.25 10.5Fun
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
Traditional 4 4.88 19.5Calculations
PBL 21 14.55 305.59.5 0.013
Traditional 4 7.5 30Tackling
problems PBL 21 14.05 29520 0.085
Table A9 Table showing results of comparison of responses between
those who preferred the traditional approach compared to the PBL
approach in semester 2 for those who had no previous chemistry
experience
Semester 2, No previous
chemistry experience
Ranks
Factor Preference for NMeanRank
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
Traditional 3 7.67 23Understanding
PBL 14 9.29 13017 0.579
Traditional 3 8.17 24.5Competency in
techniques PBL 14 9.18 128.518.5 0.738
Traditional 3 5 15Calculations
PBL 14 9.86 1389 0.116
Traditional 3 8.83 26.5Tackling
problems PBL 14 9.04 126.520.5 0.947
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