by Nicholas Arpaia, Molecular and Cell Biology
Teaching Effectiveness Award Essay, 2009
An essential concept of Molecular Immunology is experimental design. Students must understand how to incorporate appropriate molecular and biochemical techniques to answer specific questions about how the immune system functions. Teaching experimental design can be very difficult, yet results in one of those “Eureka!” moments when a student grasps how an experiment was carried out and what clues it gives about the immunological mechanism being tested. The field of Molecular Biology has expanded substantially since the 1950s, and students of the modern subject find themselves inundated with a wide variety of techniques that can be used in their designs.
The juniors and seniors taking my Molecular Immunology section (MCB 150) were challenged to design and understand experiments on exams and in section through reading of the primary literature. In the beginning of the semester it was something they definitely struggled with, as evidenced by responses to exam questions and answers to problem sets that I graded every week to probe their knowledge of experiments presented in lecture. Through these assessments I identified that I needed to implement a different teaching strategy to focus more directly on helping the students become more proficient experimental scientists.
Through their prior training in Biochemistry (a course prerequisite), they were able to understand how each technique worked, and had a basic understanding of Biochemistry and Molecular Biology; but they had difficulty applying these techniques to design their own controlled experiments targeted at answering very specific immunological questions. It was with this in mind that I designed what I called the Immunologist’s Toolbox, a running list of techniques that the students could refer to when it came time for them to design experiments. They were able to draw from this list to act like molecular MacGyvers and use the reagents that they were given in particular scenario-based questions to answer them. In each section meeting I challenged them with a new experimental question that they could answer using techniques from their toolbox. They worked together during section to design their experiments. They then presented their ideas to me, I sketched them out on the board, and we critiqued them in class.
Each time a new technique was presented in lecture or in a paper that we read, I added it to the toolbox. We also expanded on any technique that was added to the list to include recent advances or uses of the technique. This often led to greater discussions about the pros and cons of using one technique over the other in given scenarios. Our toolbox expanded far beyond the scope that I originally intended. Toward the end of the semester, we had covered everything from tissue-specific knockout mice, to siRNA-mediated gene knockdown, to the multitude of different flow cytometry techniques. For each technique, they had examples of the context in which they were originally used, and further applications.
It was clear that the toolbox was working. As the problem sets throughout the semester began to include more experimental design questions, the students were incorporating the techniques to design incredibly creative experiments. In discussion section, when I challenged them with experimental questions, it took less and less time for them to generate answers. Furthermore, it became apparent from their exams that my students excelled on these types of questions. Having taught some of the same students this semester in 150L, it is clear that they still have a handle on each of the techniques when we actually perform them in the lab. In the future, I would like to use the bSpace web tools to make the toolbox available online for the students to update and refer to.