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Learning in the laboratory: The dilemma of designing labs for first year students

Meagan Ladhams Zieba
Department of Chemistry
The University of Western Australia
Introductory and Biological Chemistry 130 is a first year course offered at the University of Western Australia (UWA) to students with a limited background in chemistry. The aim of the course is to provide the students with some exposure to and experience with basic chemistry principles. One of the more important aspects of the course is the laboratory component. These compulsory labs are designed to complement the lecture course, and to consolidate the concepts that students are learning.

When designing a lab course, most laboratory coordinators are confronted by many questions and issues, such as:

Another factor that the lecturer and demonstrators in the Introductory and Biological Chemistry course have to consider is that the students have very little background in chemistry, meaning that the first introductory labs are very important. In 2001, the students were given four lectures before starting their lab classes. In past years, students have started their labs after only one lecture. Through discussion between the lecturer and demonstrators, it was suggested that the students start their lab course in 2002 with a very general 'introduction to the laboratory' type of exercise.

Introduction

The Introductory and Biological Chemistry 130 course is a 'bridging' course, generally aimed at students who require a basic understanding of chemistry for their degree, but who have not sat the TEE Chemistry exam. Most students in this course have studied chemistry to year ten level, or it has been many years since they studied chemistry at high school. For this reason, the laboratory classes in Introductory and Biological Chemistry 130 are especially important to the students. The intention is that the laboratory work consolidates that which is taught in lectures.

The laboratory course consists of weekly lab classes, at which attendance is compulsory. Each week, the students are given pre-work questions to complete before they attend the laboratory. There is no enforced 'penalty' for not completing the pre-work prior to the class. In the laboratory class, students are required to perform a series of experimental procedures, writing observations and answering questions in a laboratory notebook, which they submit to the lab demonstrator at the end of each session. At the end of each lab class, each student completes an assessment sheet, which is designed by the lecturer to test their understandings of basic principles from the laboratory. The students' marks for the lab session are based on their performance on the assessment sheet.

Each laboratory is supervised by a demonstrator. The demonstrators are students from the Departments of Chemistry and Biochemistry, all completing either Honours or post-graduate degrees. In both semesters, half of the demonstrators were PhD students who had previously demonstrated the same course. This experience with the course meant that these demonstrators were aware of the particular learning demands of this student cohort. In addition, a roving demonstrator (also a PhD student) was present. This demonstrator moved from class to class, assisting students where required.

Background

As a laboratory demonstrator in this course in 2000, I found that many of my students had difficulty with the laboratory work. Although some difficulties were to be expected, based on the students' levels of chemistry study, the general consensus amongst the demonstrators and the course lecturer was that some of the laboratory instructions were too verbose and difficult to understand. In trying to interpret the laboratory exercise, the students were losing the 'signal' in the 'noise' (Johnstone, 1984).

As an example to illustrate this, in the first section of the first laboratory exercise, the students are asked to do the following:

These instructions are given to the students after a three-page introduction, which includes several pre-work questions. In 2000, the students began their lab work in the first week of semester. This meant that on either their second or third day at university, they were being faced with a multitude of instructions of the sort shown above.

The chemistry illustrated in the experiment isn't particularly complex, but for our students, it is tough going. As a chemist, I find the instructions above simple to follow. Weigh out copper, add some concentrated nitric acid to it, and write down what you see. This is an example of 'chunking' information (Johnstone, 1997), which helps me understand and process the instructions given in the laboratory. Many of the students in the lab class could not 'chunk' the information presented to them in this way. They had to ask what a 'top loading balance' was, and which bits of glassware were the beakers. Then they had to ask where the concentrated nitric acid was. "Is this stuff on the bench ok, Meagan?" one student asked me. The simple answer to his question was "no". To explain the answer fully, I needed to tell him about the differences between concentrated and dilute acids.

The study

As a part of the University of Western Australia's Teaching Internship Program in 2001, I was involved in re-writing and re-ordering some of the exercises in the laboratory classes. One of these changes involved removing a laboratory class, so that the students would begin their lab course in week two of semester, after four or five lectures. Anecdotal feedback from the students indicated that starting the laboratories in week two was beneficial, as it gave them a chance to 'settle in' to the course before commencing lab work. The laboratory classes themselves were still demanding for the students. A survey, administered to two tutorial classes (52 students) in the fourth week of semester, asked the students the following questions about the first two labs of the semester: The majority of the students indicated that they had enjoyed the first two laboratories, although many of them did find the lab work and assessment sheet to be somewhat difficult. Most students labelled their prior knowledge as 'non-existent' or 'basic' before the lab, which improved to 'basic' or 'good' after completing the lab.

Students were also asked to add any written comments about the lab work in general. The following are examples of the comments made:

The knowledge and understanding required to complete the lab work, especially the assessment sheets, are not acquired until sometime after the lab.

Too long. Found it hard to complete the lab and assessment sheet in required time.

Would like to have some set aside time to go through pre-work if having trouble.

Having never done any chem before, this lab was very, very challenging and I found it very hard to keep up with the rest of the class.

In their final lab class, 63 of the students were surveyed to find out which labs they had liked the most, and which they had liked the least. About a third of the students said they had no particular favourite, or 'least favourite', lab. Many of the students gave 'time constraints' as a reason for disliking particular labs. Another common comment was that some of the labs were 'too hard' or confusing. Students' most common reasons for enjoying a lab class were that the chemistry was interesting; or that they perceived the laboratory to be easy to understand.

A meeting between the demonstrators and the lecturer after the completion of the lab course resulted in a new 'Introduction to Chemistry' laboratory session, which the students would complete as their first lab exercise. This laboratory practical is attached as Appendix 1.

'An Introduction to Chemistry' has been designed to introduce students to the concepts of ionic solids and solutions. Inherent in this is the notion that compounds with different appearances may have very similar chemical compositions. The lab also aims to familiarise students with the use of formulae and symbols in Chemistry. It is anticipated that this will assist the students in their second laboratory, when they are required to write chemical equations. In addition, students will be getting some experience in making and recording chemical observations, an important skill they need to develop in first-year Chemistry. During the exercise, questions in the text prompt students to immediately record their observations.

The students will perform this lab for the first time in week two of first semester, 2002. It is designed to be a fairly short class. This will enable the students to get to know their demonstrator and their classmates, and to familiarise themselves with the laboratory classroom and the equipment they are provided with. This chance to become acquainted with their classmates, demonstrators and laboratory will help to foster a supportive learning environment for the Introductory and Biological Chemistry students.

In response to students' comments, several other laboratories will also be revised: some will be shortened, others will have their language and instructions simplified. These modifications will be made in collaboration with the course lecturer, to ensure that the lab course continues to reinforce the concepts being taught in the lectures.

Conclusion

A laboratory exercise was prepared for the Introductory and Biological Chemistry 130 course at the University of Western Australia, which will be performed by students as the first lab in semester one, 2002. The lab has been designed specifically as an introduction to basic equation writing and chemical observations for the students in this bridging course. Other lab exercises in the course will also be modified and simplified, following discussion with the lecturer, demonstrators and students.

References

Johnstone, A. H. (1984). New stars for the teacher to steer by? Journal of Chemical Education, 61(10), 847-849.

Johnstone, A. H. (1997). Chemistry teaching - Science or alchemy? Journal of Chemical Education, 74(3), 262-268.

Laboratory Notes for Chemistry 121 and Introductory and Biological Chemistry 130 (2000). Department of Chemistry, The University of Western Australia.

Appendix 1

An Introduction to Chemistry

Hazards: Solutions and solids containing lead (atomic symbol Pb) are toxic, so take care when handling these compounds. Hydrochloric acid (HCl) is corrosive. If you spill any on yourself, wash your hands under plenty of cold water. Be sure to advise your demonstrator if you spill any solutions on yourself, or if you break any glassware.

Aim

To give you an opportunity to become familiar with the laboratory and to perform some short experiments. These experiments will also give you some experience with making and reporting chemical observations.

Part One


Collect 10 mL of sodium chloride solution in a test tube.
Q1.Describe what the solution of sodium chloride looks like. Be sure to mentioned any colour or odour that the solution has.

Collect a sample vial of solid sodium chloride, NaCl(s).
Q2.Describe the solid sodium chloride.
Q3.How are the solution and the solid similar? How are they different?

Add 10 mL of distilled water to the sample vial of sodium chloride.
Q4.Describe what happens to the solid.
Q5.How is this solution and the solution of sodium chloride similar? How are they different?

Part Two


Collect a sample bottle of solid anhydrous copper sulfate (CuSO4 (s)), and a sample bottle of solid copper sulfate pentahydrate (CuSO4.5H2O(s)).
Q6.Describe the solid anhydrous copper sulfate. Describe the solid copper sulfate pentahydrate.
Q7.How are these two solids similar? How are they different?

Add 10 mL of distilled water to each of the vials.
Q8.Describe both solutions. Are the solutions the same, or different? Explain.

Part Three


Place a small piece of zinc metal (Zn) into a test tube.

Carefully add 5 mL of 2M hydrochloric acid (HCl) to the metal.
Q9.What do you observe happening?
Q10.Where has the metal gone? Was anything produced in the reaction?

When gases are produced in a reaction, there are several tests that can be performed to identify the gas. Your demonstrator will show you how to do a 'pop test'.
Q11.What type of gas does this identify?

Part Four


In two separate test tubes, collect 10 mL of 2M lead nitrate (Pb(NO3)2) solution, and 10 mL of 2M sodium iodide (NaI) solution.
Q12.Describe these two solutions.

Carefully pour the two solutions into a clean beaker.
Q13.What do you see happening? Make sure you describe any colour changes that result from mixing the two solutions. What do you think is being produced?

Author: Meagan Ladhams Zieba, Teaching Intern, Chemistry, The University of Western Australia
meagan@chem.uwa.edu.au

Please cite as: Ladhams Zieba, M. (2002). Learning in the laboratory: The dilemma of designing labs for first year students. In Focusing on the Student. Proceedings of the 11th Annual Teaching Learning Forum, 5-6 February 2002. Perth: Edith Cowan University. http://lsn.curtin.edu.au/tlf/tlf2002/zieba.html


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