The Nature and Variability of Children's Alternative Conceptions of Evolution
In recent years a large amount of research has focused on the alternative conceptions about evolution found among secondary and university students, but few studies have investigated younger students' ideas on this subject. The present study examines the alternative conceptions of evolution harbored by second and third-grade students who participated in a summer instructional course that scaffolded the mechanisms of natural selection through cases of microevolution. In order to identify the categories of alternative conceptions that students expressed, 60 sets of pre- and posttest structured interviews were analyzed, and these showed that participants in this study expressed alternative conceptions closely related to those identified in studies conducted using high school and college-age participants. The results demonstrated a variability of alternative conceptions across a range of interview items, and also revealed how contextual features in the assessment tasks may account for the patterns that emerged in students' responses. Students' evocations of alternative conceptions declined after their participation in the instructional course. The analyses of the four case study students, whose pre-and posttest patterns were representative of their cohorts, provided a detailed within-subject look at how these alternative conceptions occurred in the context of the interview items and how they changed from pre- to posttest. These findings have broad relevance to understanding conceptual development in young children and important implications both for considering at how early an age instruction about evolutionary biology should begin and for evaluating the potential long-term impact of a curriculum that targets sources of student difficulty at earlier grade levels.