UNDERSTANDING EVOLUTION: VARIATION BETWEEN HIGH SCHOOL AND COLLEGE STUDENTS

Students at all academic levels struggle to understand and reason about evolution. A stumbling block for students may be a lack in understanding of natural selection, which is a principle mechanism of evolution. To investigate student understanding of evolution by natural selection we used a modified Bishop and Anderson Open-Response Instrument (ORI) prompt which should elicit five key concepts of natural selection (variation within a population, origin of variation, inheritance, fitness, and change in populations). In this study high school and college students received a trait gain and trait loss prompt pre- and post- instruction. High school students (n=74) were enrolled in a 10^th grade biology course with a unit on evolution. College students (n=77) were enrolled in an introductory geology courses for non-science majors where evolution was a minor unit. Student responses were coded using a modified Bishop and Anderson rubric, which identified the presence and correctness of five key principles of natural selection

Student responses were coded a ‘0’ if the key principle was absent, ‘1’ for incomplete, or ‘2’ for correct. Presence and correctness for each key principle was low in the pre- and post- for both assessments. On the trait gain question there was no significant difference in presence (p = 0.339) for the high school students. There was a significant difference from pre- to post- assessment for correctness (p = 0.016), and the key principle ‘variation’ drove this difference. There was no significant difference for presence (p = 0.056) or correctness (p = 0.423) in the college students' pre- and post- responses.

Overwhelmingly, high school and college student tended to include one key characteristic in their responses (i.e., were given a ‘1’ or ‘2’): variation within a population. These results suggest that students struggle with identifying and using the key principles in natural selection. They do not include or correctly use all the key principles, and generally only include one or two of the five principles.