Teaching Assistants (TAs) in the Laboratory
It is no secret that effective teachers can make a significant
impact on the students’ learning experience. The Department
of Chemistry in NUS deploys postgraduate students as Teaching
Assistants (TAs). These TAs are largely ‘laboratory
demonstrators’, who assist the academic staff in demonstrating
laboratory techniques to undergraduate students during practical
(laboratory) classes. Conversely, it has been observed in
NUS, and reported widely in chemistry education literature,
that when students perform chemistry experiments, they often
focus too narrowly on the manipulative tasks at hand and do
not give much thought to the principles behind the experiments.
As a result, students understand and learn very little from
the laboratory classes. In this paper, we will describe a
study conducted to improve the students’ learning experience
in laboratory classes involving TAs. Other useful findings
from the study will also be discussed.
A Quasi-experimental Action Research Study
CM1121, “Basic Organic Chemistry”, is an essential
module offered to students from Chemistry, Life Sciences,
Engineering and various other majors in both semesters of
the Academic Year. Students complete laboratory tasks such
as synthesising compounds, separating mixtures and identifying
the functional groups in known and unknown compounds during
the 15 hours of required practical work.
In Semester 1 (Academic Year 2003/2004), 554 students (mainly
Life Sciences students) enrolled in CM1121. This paper describes
a quasi-experimental action research study carried out on
79 students of which 37 were assigned to the Experimental
group and 42 to the Control group. These students had obtained
similar ‘A’-level (or equivalent) results in Chemistry.
Students in the Experimental group received ‘intervention’
(as described in the next section, ‘Improving Students’
Laboratory Experience’) during their laboratory sessions,
but those in the Control group had their laboratory sessions
conducted in the traditional manner (i.e. no ‘intervention’).
Two consecutive tests were designed and administered to measure
the students’ knowledge of the experiments and their
understanding of the principles behind the experiments towards
the end of the semester. A survey questionnaire was also administered
to assess their learning experience in the laboratory. Finally,
follow-up interviews were conducted with some students in
the experimental group to collect qualitative information.
Table 1 shows a brief summary of the activities that took
place over the five CM1121 laboratory sessions:
Table 1: CM1121—Activities of the
five laboratory sessions
*Experiment 3 was not included as part of this study,
due to deadlines for completing the Honours Year project.
Improving Students’ Laboratory
For students in the Experimental group (taught by the first
author), each laboratory session was generally conducted as
- Worksheets were only distributed to the students before
a session began. These worksheets were uniquely designed
to present vital aspects of a new experiment in a way that
related the experiment to what the students had learnt before
so that they could better integrate the new information
into their existing knowledge networks. In addition to using
diagrams to illustrate abstract concepts, a number of thought-provoking
questions were included to encourage the students to think.
Although the first author provided some answers, students
answered most of the questions after discussing among themselves.
- A laboratory instructor (i.e. academic staff) would begin
a laboratory session with a standard pre-laboratory briefing
for students from both the Experimental and Control groups.
Then, students in the Experimental group, who had received
the worksheets prior to the briefing, would be taken aside
by the first author for a preliminary discussion of the
worksheet. These students would then pair off to perform
the experiment. A discussion would be held at the end of
the experiment where students would share their answers
to the questions on the worksheet.
- As an additional effort to stimulate thinking, the pairs
of students were told to vary the value for one of the variables
in the experiment so that they could witness collectively,
how the variable affects the results.
Statistical significance at the 0.01 level was obtained
in analysing the students’ test scores using the two-tailed
Table 2: Analysis of Students’
Scores on Test 1
Note: The maximum possible score for Test 1 is 30.
Table 3: Analysis of Students’ Scores on Test 2
Note: The maximum possible score for Test 2 is 80.
In the survey questionnaire, students were asked to rate
some statements on a five-point scale. These statements can
essentially be categorised according to three main issues:
- How well the students have understood the experiments.
- Their attitudes towards laboratory work (e.g. was it
boring or difficult?).
- Their perceived ability in mastering laboratory techniques.
The responses of students from the Experimental group had
more positive views on all three issues as compared to those
from the Control group.
In addition, the interviews yielded the following information:
- Most students in the Experimental group exhibited a rather
substantial understanding of the experiments based on the
verbal explanations provided (upon request) for their answers
to the test questions.
- Though some students answered the test questions incorrectly,
this was largely due to false assumptions or misconceptions,
which were difficult to overcome within the short period
- The worksheets and the guidance from the first author
had helped students to earn both the conceptual and technical
aspects of the experiments.
- Varying the values of some variables in the experiments
had made the laboratory sessions more interesting for the
students as they could witness and discover new results
instead of reproducing known data.
Implications and Recommendations
Role of TA in the laboratory
In this study, the first author succeeded in making a significant
difference to both the students’ academic achievements
and their attitudes toward laboratory work by using various
strategies to enhance their learning experience. It should
be noted that any TA, whose commitment to teaching is similar
to that established by the first author, can make an impact
on the students’ learning experience. This calls for
possibly, the establishment of a set of selection criteria
focusing on the teaching commitments of a TA (e.g. the minimum
number of hours that a TA is required to teach, participation
in a training programme that raises the TAs’ awareness
of their role in improving the students’ learning experience,
particularly in the laboratories).
Management of learning activities
Literature on education states that careful organisation
and sequencing of activities are essential in the facilitation
of meaningful learning. In this study, the first author structured
the information on the worksheets before presenting it to
the students. Therefore, students could integrate the new
knowledge with their existing knowledge better. In addition,
it is important to reinforce the key concepts introduced in
previous experiments by revisiting or representing these ideas
in different contexts in subsequent experiments. The series
of worksheets had this feature built-in.
Since there is a shift in emphasis from performing mechanical
tasks to illustrating the principles behind the experiments
to the students, we should perhaps adjust the time allocated
for these activities accordingly. Though performing mechanical
tasks is essential in developing the students’ competency
in laboratory techniques, these tasks could perhaps be done
outside the formal laboratory hours so that more time could
be devoted to what is important during the formal laboratory
hours. Adopting an open laboratory policy where students can
return to the laboratory to finish the mechanical tasks at
their convenience is one possible solution.
According to literature on science education, students’
laboratory experiences should be pivotal to their learning
of the subject because the laboratory is a place where the
students learn how to ‘do’ science. However, many
students’ laboratory experiences do not include the
part on doing ‘real’ science. In fact, laboratory
work (especially in lower-level coursework) has been given
a reduced emphasis. It appears that such could be the result
of (at least on the students’ part) a fear of performing
dangerous acts in the laboratory due to insufficient experience
and the lack of available guidance. With a good supply of
postgraduate students, who can be deployed as TAs (although
careful selections must be made to ensure the quality of their
service and to avoid derailing them from completing their
postgraduate studies), and a carefully designed curriculum,
the students’ learning experience in the laboratory
can be improved.
The authors would like to thank Dr Lam Yulin, Ms Wong
Nguk Yeng and Ms Teh Yun Ling from the Department of Chemistry
for their assistance and contributions.
* The study reported in
this article is based on an Honours Year project in Chemistry
completed recently by Lau Wan Yung. He was serving as a Teaching
Assistant for the module CM1121, “Basic Organic Chemistry”
while conducting this study.