by Daniel Bliss, Molecular and Cell Biology (Home Department: Helen Wills Neuroscience Institute)
Teaching Effectiveness Award Essay, 2013
Before the first exam for MCB160: Introduction to Neurobiology, the head professor expressed concern to me that one of his questions might be difficult for the students. I didn’t know what to think, because the question fell within the topics he’d covered and seemed straightforward to me, someone who hadn’t known much about the course material before becoming a GSI. He was right, however, that an explicit answer would not have been found in the lecture slides. What was different about this question was that it asked the students to design an experiment. For this they would not be able to rely on rote memorization of facts already known, but would need to reason about how new information might be acquired — a skill fundamental to the scientific method.
As the professor feared, many students missed that question. The prompt asked for an experiment that would distinguish between two alternative hypotheses, but in many cases what the students did was assume one of the alternatives, describe a detailed model of the biochemical mechanism that might underlie that alternative, and, almost as an afterthought, sketch an experiment that would reveal one step in that mechanism. Their proficiency at internalizing and recalling textbook-level explanations had led them astray. My challenge, I realized, was to help them be able to switch into the thinking mode of an experimenter when they needed to.
At the next week’s discussion sections I took fifteen minutes to walk the students through the logic of experimental design and interpretation. I presented a toy experiment I’d designed, on a different topic from lecture, in which I hid the assumption of a mechanism, and interpreted the ambiguous results of the experiment to support this mechanism. Rather than point out the error to them, I had the students make a diagram on the chalkboard that represented the logical steps I had taken in drawing my experiment’s (unjustified) conclusion. Once the diagram was complete, the students spoke out unanimously to identify the error. This confirmed for me that the students could reason well; they just weren’t used to having to think this way in their science classes.
In subsequent discussion sections, I asked the students to plan experiments that would address questions raised in one lecture, using techniques explained in another. Sometimes we would draw experimental scenarios on the board, and I would ask them to fill in graphs with what their data might look like, and what conclusions would be implied. Their skill at these exercises improved to the point that I was able to elicit experiments from them that had recently been published in Nature, without their ever having been aware of the paper. Questions like the one on that first exam appeared in tests and quizzes throughout the semester, and the students’ answers improved noticeably, losing extraneous detail and concisely summarizing the important logic.
Aside from test scores, I received evidence that the students had grown from being able to understand and remember facts presented to them, to being able to think critically about how those facts were discovered. Recently I encountered one of my former students, and he mentioned having just completed an evaluation of the MCB Department, given to all seniors. One question asked whether he had been taught to think logically and critically. Giving perhaps the most encouraging feedback I’ve received, he said the first thing that came to mind in answering that question was my discussion section after our first exam.