Scaffolding preservice science teachers' evidence-based arguments during an investigation of natural selection

In this qualitative case study, preservice science teachers (PSTs) enrolled in their advanced methods course participated in a complex, data-rich investigation based on an adapted version of the Struggle for Survival curriculum. Fundamental to the investigation was the use of the Galapagos Finches software and an emphasis on giving priority to evidence and constructing evidence-based arguments. The questions that guided the research were: (1) What is the nature of the scientific arguments developed by PSTs? (2) How do PSTs go about constructing scientific arguments (emphasis on processes and strategies)? (3) In what ways do the scaffolds embedded in the Galapagos Finches software influence the development of PSTs arguments? Two pairs of PSTs were selected for in-depth examination. The primary sources of data were the electronic artifacts generated in the Galapagos Finches software environment and the videotaped interactions of both pairs as they investigated the data set, constructed and revised their arguments, engaged in peer review sessions, and presented their arguments to the class at the end of the unit. Four major patterns emerged through analysis of the data. First, using the software, PSTs consistently constructed claims that were linked to evidence from the investigation. Second, although PSTs consistently grounded their arguments in evidence, they still exhibited a number of limitations reported in the literature. Third, the software served as a powerful vehicle for revealing PSTs knowledge of evolution and natural selection. Finally, the PSTs approach to the task had a strong influence on the way they used the software.