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) What characteristics of the graphs show that there was variation in the population? How much variation was in the population in 1976? How much variation was in the population in 1978? 2) What happened to the population size between 1976 and 1978? What other changes occurred in the population? 3) Based on the data, what is the approximate average beak depth of the population in each year? Natural selection in Darwin’s finches

Understanding Evolution: Problem-based discussion 4) Based on these limited data, which mode of selection seems to have operated on the finches? What evidence supports this idea? 5) What do you hypothesize could have caused this change between 1976 and 1978? Describe a possible ecological relationship between drought and beak size. 6) Assume the drought continues for another 2 years,. If natural selection is occurring, what would you expect to see in future generations? If the changes in beak size are not due to natural selection, but to drift, then what would you expect to see in future generations? Natural selection in Darwin’s finches