Students' use of evidence and epistemic criteria in model generation and model evaluation

The Next Generation Science Standards and the Framework for Science Education emphasize the importance of engaging learners with the core scientific inquiry practices of modeling and argumentation. Students are also expected to understand the epistemic grounds and norms that accompany these practices. We report on a study in which we engaged middle school teachers, and their students, in model-based inquiry, with particular emphasis on developing models and evaluating competing models using evidence. Analysis of students' written arguments, in the context of an assessment task in genetics, suggests that students use both secondary epistemic criteria, relating to communicative features of models (labels, drawings), as well as primary epistemic criteria, relating to evidence-model fit. Most students used at least one, and often several, provided pieces of evidence to support their arguments. We also discuss some instructional implications and tradeoffs in selecting evidence for such model generation and model evaluation tasks.