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

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:

• What type of (and how much) information should be given to the students as pre-reading?
• How can we ensure that students do their required pre-work?
• How do we assess students in the lab?

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

• On a top-loading balance weigh out into a weighing-tray approximately 1.5 g of copper metal, record the mass, and transfer the copper to a 250 mL beaker.
• With care, measure out 15 mL of 8 mol L^-1 nitric acid (HNO₃) in a measuring cylinder. IN THE FUMEHOOD, pour the acid solution into the beaker containing the copper. THE GAS FORMED IS POISONOUS. Its colour and stink indicate it to be nitrogen dioxide (NO₂).
• Place a clock glass on top of the beaker.
• As the reaction proceeds, record your observations. Allow the reaction to continue until all the copper metal has disappeared.
  (Laboratory Notes, 2000, p 4)

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

• Did you enjoy doing this lab?
• How difficult did you find the laboratory work and questions in this lab?
• How difficult do you think the questions on the assessment sheet were?
• How would you rate your understanding of the chemistry covered in the laboratory before and after the lab?
• Did you feel that there was enough material covered in the lectures and the tutes before and after this lab to help you understand what the lab was intending to teach?

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.

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

References

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