Understanding Evolution: Problem-based discussion For the instructor: Pedagogical research indicates that students learn better if they are actively engaged. The following slides require only a few minutes each and are designed to actively engage students with lecture material on the topic of evolution through discussion. Problem-based discussions are a valuable active learning technique that involves students teaching each other, thus promoting student engagement and learning. In this technique, the instructor posts a written description of a scientific problem or a diagram, table, or graph relevant to a topic under consideration. The instructor provides a list of questions that students should work to answer. Students then spend 5–10 minutes, first thinking individually about the questions in reference to the problem or figure, and then pair up and take turns explaining their answers to each other and filling gaps in each other’s knowledge. At the end of the discussion, the instructor can read aloud the questions, either verbatim or modified to be slightly different, and ask whether students are confident they could explain the issues to each other. The instructor may wish to call on students to answer individual questions, or may ask if the discussion raised any questions they would like to ask in class. This slideshow is provided by Understanding Evolution (understandingevolution.org) and is copyright 2011 by The University of California Museum of Paleontology, Berkeley, and the Regents of the University of California. Feel free to use and modify this presentation for educational purposes.

Understanding Evolution: Problem-based discussion 1) Explain what is shown on the x- and y-axes. 2) Choose two lines on graph A, one that goes to the top of the graph and one that goes to the bottom. For each line, explain what the line represents and how it changes over time. Also, explain what it means when a line goes to the top of the graph versus what it means when a line goes to the bottom of the graph. Population genetics simulation of drift

Understanding Evolution: Problem-based discussion 3) Explain the difference between the simulations that generated graphs A and B. 4) Why do y-values fluctuate in each graph? Population genetics simulation of drift

Understanding Evolution: Problem-based discussion 5) In graph A, how many of the trials resulted in a frequency of A = 1.0 and how many resulted in a frequency of a = 1.0? Why might this occur? 6) The populations represented by graph A and graph B demonstrate very different behavior. What concept regarding genetic drift does this illustrate? Population genetics simulation of drift

Understanding Evolution: Problem-based discussion 7) If one allele were under selection in graph B, how would this graph differ? 8) For each population represented on graph A, would you expect the population to be in Hardy-Weinberg equilibrium? For graph B? Population genetics simulation of drift

Understanding Evolution: Problem-based discussion 9) How would each of these graphs differ if starting allele frequencies in the simulations were not 50/50—for example, if the populations began with 30% A alleles and 70% a alleles? Would drift occur? Population genetics simulation of drift