|Teaching and Learning Forum 2002 [ Proceedings Contents ]|
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.
- 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?
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.
As an example to illustrate this, in the first section of the first laboratory exercise, the students are asked to do the following:
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.
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.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.
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.
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.
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.
|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.|
|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?|
|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.|
|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?|
|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|
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