Evolutionary Ecology

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Bruce Grant began his presentation by emphasizing the importance of addressing students' alternative conceptions of evolution. He noted that the United States ranked near the bottom in a recent comparative international study on the proportion of the public that accepts the theory of evolution. Grant suggested that this lack of acceptance of a well supported theory reflects a larger ideological struggle in American society over the basic concept that evidence matters. He explained that he was motivated to change his teaching approach because of these concerns and because a large proportion of students fail introductory biology classes or drop biology as a major field of study.

Grant then described his practitioner research, arguing that it has improved his freshmen students' conceptual acceptance of evolution by natural selection. He has conducted research on student learning among eight cohorts of freshmen enrolled in an evolutionary ecology course each year from 2000 to 2007, revising the course based on his research. He observed that, because practitioner research incorporates many aspects of traditional scientific ...
... epistemology but excludes other aspects, it constitutes a unique and complementary "way of knowing" that can improve science teaching and student learning.

Grant said he administered a standardized final examination at the end of the course each year to assess student learning and their response to his course revisions. The examination includes the prompt, "Please offer a brief and concise definition of evolution." Since 2005, he has also used this prompt as a pretest. In addition, he has administered a standardized assessment item designed to measure students' conceptions about evolution.

Beginning in fall 2005, Grant conducted frequent short-answer surveys of students' preconceptions about key topics before they were discussed in class, but the assessment results showed only slight improvement in the learning of basic concepts. Beginning in fall 2006, Grant directly confronted his students with their alternative conceptions, as indicated by their responses to the short-answer surveys and the pretests. He presented students with histograms of their responses and, at the same time, revised the course syllabus to address the alternative conceptions. In addition, he asked them in guided discussions to reflect on the kinds of evidence and arguments he should present that would help them understand the key topics. Finally, he substantially reduced the content and shifted class time toward increased writing and classroom discourse.

These changes yielded significant gains in student learning in the more recent classes, in comparison with earlier classes. The fraction of correct responses to the prompt, "Please offer a brief and concise definition of evolution" rose from about 50 percent in the period 2000 to 2005 to 90 percent in December 2006 and 80 percent in December 2007. Students' mean scores on the standardized final exam went from 6.44 in December 2002 to 9.51 in December 2006 and 8.79 in December 2007. Grant also found large gains in student scores on the standardized question on evolution. From 2000 through 2005, only about 3 percent of students scored 8, 9, or 10 on this 10-point question, but in 2006 and 2007, about 54 percent achieved a score of 8, 9, or 10. The mean scores on this item also improved significantly, from 4.38 to 7.36.

Grant concluded that the revisions he instituted in fall 2006 significantly decreased students' misconceptions and improved their learning about the concept of evolution and the process of evolution by natural selection. In addition, he learned new approaches to teaching that rely on the evidence generated by his practitioner research. He promised to continue to redesign and improve the course and described plans to increase his use of published concept inventories and to engage students in research on their own learning. He encouraged other STEM faculty to engage in practitioner research.

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