Providing vertical coherence in explanations and promoting reasoning across levels of biological organization when teaching evolution

Jördens J., Asshoff R., Kullmann H., Hammann, M.

Abstract

Students' explanations of biological phenomena are frequentlycharacterized by disconnects between levels and confusion oflevels. The purpose of this research is to investigate the effects ofa hands-on lab activity that aims at fostering the ability to reasonacross levels. A total of 197 students (18 years of age) participatedin a randomized, pre-post-test design study. Students in theexperimental group engaged in a lab activity focused on artificialselection and designed to demonstrate how selection affects bothphenotypes and genotypes. In contrast, the lab activity in thecomparison group focused on phenotype alone. Data sources forthe study included pre-tests of basic concepts in genetics andevolution and two post-test items requiring the students toreproduce and apply their knowledge about artificial selection.The findings indicated that the lab activity which allowedstudents to explore the interplay between different levels,provided vertical coherence and enhanced students' ability toexplain evolutionary change in both reproduction and transferitems. In contrast, the lab activity in the comparison group failedto do so, and most students did not improve their ability toexplain evolutionary change. Implications for instruction andrecommendations for further research are discussed in light ofthese findings.