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 Experience

For students in the Experimental group (taught by the first author), each laboratory session was generally conducted as such:

• 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.

Results

Quantitative results

Statistical significance at the 0.01 level was obtained in analysing the students’ test scores using the two-tailed independent t-test.

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.

Qualitative results

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 of ‘intervention’.
  
  
• 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.

Conclusion

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.

Acknowledgments

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.