Use of clicker questions in the flipped lecture

The design and delivery of clicker questions is a key feature of a flipped class. I am getting ready to teach the fourth instance of my flipped genetics (BIS101) at UC  Davis and as I review the material I reflected on the challenge of the clicker questions. My lecture-discussion on RNA interference is a good example. The lecture objective is to get the students to understand how a genetic screen involving a micro RNA gene would work, how one would analyze it, and what conclusions could be drawn from it. In summary, a key moment in the climb of Bloom Taxonomy of Learning peak.  

At this point in the course, students have learned Mendelian genetics, the central dogma, prokaryotic gene regulation and are learning eukaryotic gene regulation. In preparation for the lecture-discussion students have viewed online material featuring both description and videos of RNA interference. In addition, I provide a short seminar by Gary Ruvkun, which while very clear, turns out to be very challenging for many of my students.  

The objective of the two-hour lecture-discussion is for students to understand how an imaginary genetic screen involving lin-4 and lin-14 would have worked. For those who are not worm connoisseurs,  lin-4 is a mutation affecting a miRNA that targets the mRNA of lin-14, which product promotes larval cell growth. lin-4 mutants have excess larval cells. lin-14 mutants fail to develop certain larval cells. lin-14 is epistatic over lin-4. The two mutations were isolated independently, but in this class I openly pretend that lin-14 was isolated as a modifier of lin-4. 

A cartoon depiction of a fictional genetic screen in which the neotenic lin-4 phenotype is suppressed by the progeric lin-14 phenotype

I have uploaded a video of the whole lecture-discussion (see below). The video demonstrates the importance of carefully planning the Socratic process of teaching. It displays both success and (partial) failure. Success is illustrated by a series of clicker questions on how a miRNA and target interact, starting here.  As illustrated by the response to this clicker question, students respond well and are getting the concepts. 

One of several clicker questions exploring the concept of how a miRNA and its target interact to provide a new regulatory outcome. Students did very well.

Failure is illustrated by the difficulty in getting students to work through pathway analysis starting with an F2 segregation pattern consistent with recessive epistasis. The problematic phase starts here.

Many students were stumped. The problem with this clicker question is not intrinsic to it: it is a good question. However, in the instance demonstrated in the video, it should have been preceded by a refresher on epistatic analysis. For example, a few easier clicker questions that review it.  

The problem is clear: I jumped into the 9:3:4 F2 ratio and the connected pathway without "warming up" the students. The transition was too abrupt. We had covered this type of analysis a few weeks before and students had done well. I should have make a quick example of epistasis, reminding students of the symbols (such as --| for repression and --> for promotion), and of the strategy used to test hypothetical pathways using mutant phenotypes. Also, this question was delivered in the second hour and fatigue may have also contributed.

All considered, this lecture-discussion was not a flop. The students understood much of it and were reminded that genetic experiments are carried out to understand cellular mechanisms. Following this lecture, they used online quizzes and material to review the problems and eventually did well in the exams.

The moral of the story is that the clicker questions must be designed and delivered very carefully. If done properly, the process is very satisfying because students engage and learn to extrapolate simple knowledge and analyze scientific evidence to derive mechanisms.