Examining how classroom communities developed practice-based epistemologies for science through analysis of longitudinal video data.

Recent reforms in science education emphasize having students develop and refine core disciplinary ideas through participation in science knowledge–building practices. Supporting students’ meaningful participation in these practices is challenging, in part because our understanding of how this kind of participation develops is underexplored. This paper characterizes the epistemic dimension of classroom scientific practice—the underlying assumptions and criteria guiding students’ knowledge-building work—in moment-to-moment interactions, and how their use of these criteria shifted over time. These patterns of change illustrate how, by 8th grade, students were more consistently using sophisticated disciplinary forms of epistemic criteria than they were in 6th grade. The shifts toward disciplinary sophistication were cumulative over time and across content areas, suggesting that they reflected a shift in something other than content knowledge gains. Yet these cumulative shifts did not occur in a clean, predictable progression toward sophistication. This study documents the details of these shifts over time and across content areas. By providing an empirical account of the evolution of students’ knowledge-building work in practice over time, this study argues for the centrality of epistemic learning goals in science education and proposes implications for how to measure and support students’ meaningful participation in scientific practices in contextually valid ways.