Linking Theory and Experiment in a Biochemistry Lab
by Giulietta Spudich, Molecular and Cell Biology

I encountered a problem when faced with teaching my section of MCB 110L (a biochemistry laboratory). Three afternoons a week, my 18 students were asked to perform experiments addressing a main question. These experiments were described in the lab manual, but the protocols were not spelled out. I noticed in the first couple of labs that my students were divided in how they approached the lab manual. Some could easily extract the protocols from the description of the experiments, bringing a "recipe" to class, which was great for the practical side of the lab. These students, however, were in general not as good at understanding the mechanisms or hypothesis we were testing. A second faction of the lab had the opposite problem, in that they understood the reason for doing the experiment, and the scientific theory, but they had little idea of how to actually go about doing the experiment! I wanted the first set of students to understand why we were performing the experiments, and the second set to learn how to devise a protocol from an experimental description. However, we were faced with limited time to perform the experiments, and the students could easily finish their tasks without thinking about the theory behind the practical side of the laboratory.

I approached this problem in a couple different ways. First, I had all the students bring to class a written "recipe sheet," or protocol, for the experiment we were about to embark upon. I then took 15 minutes at the beginning of each lab to write the protocol on the board, and to go over it with the class step by step. This forced the students to try and come up with the protocol themselves, and compare it to the one written on the board so they could learn how to translate a lab manual into a protocol.

The second half of the problem was a little harder to address, as the students could complete their weekly lab tasks without really understanding the theory behind the experiments, so it was hard to force them to think about the "why" of the experiments. To approach this problem, I used the students who already had strengths in the theory by interrupting my discussion of the protocol to ask the students why we were doing certain steps. The more theoretically minded students would answer, providing insight to the class. I was attempting to get the students to link the "why" behind the experiment to the practical side of the laboratory.

To ascertain that the students’ skills were improving, I would walk around the lab as they performed the experiments, and ask the students to see their protocols. I noticed they were getting better at listing the steps they needed to carry out, and their protocols were more organized. I was also getting fewer questions about the practical side of the lab from the students, and more questions about the theory behind the experiments. What’s more, some students actually started asking me in the middle of my explanations why we were doing certain things, showing that they were beginning to think in a more scientific fashion instead of blindly going about the lab. Finally, it was clear in the 10 minute oral exams we had to give them throughout the semester that the students were understanding the basis for the experiments, and could even start to propose alternative experiments that would test the same questions.