Developing mechanistic model-based explanations of phenomena: Case studies of two fifth grade students' epistemologies in practice over time

To foster meaningful engagement in scientific practices within classrooms, we must better understand how students can productively develop their epistemologies in practice (EIP) across contexts. This study traces how two high-performing fifth grade students engaged in scientific modeling across three modeling-centered units over one and a half years. To analyze their epistemologies in practice over time, we examined their model-based explanations and reflective talk about the rationale and purposes of their explanations. While both students developed more mechanistic explanations of phenomena, they did so in different ways. One developed a meta-level rhetorical strategy to explain "how and why" phenomena occurred, even in non-prompted contexts. The other used a reductionist analytical strategy to look for deeper level mechanisms of phenomena. These cases provide evidence that students develop EIPs across contexts, and leads to insights about what develops, what might influence this development, and how EIPs can be further supported in classrooms.