There has been an emphasis in science education reform documents on the practices of science for many years (NRC, 1996, 2000, 2007, 2012) and most recently, the Next Generation Science Standards (NGSS Lead States, 2013) framed participating in science practices and discourses of science as a critical part of students’ science learning. Related research in science classrooms has demonstrated the importance of discourse (Kelly, 2011; Kelly & Crawford, 1997; Lemke, 1990; Roth, 2005), and how participating in authentic discourse forms a core part of participation in a disciplinary community (Lemke, 1990). The ways in which teachers engage students in talking science (Lemke, 1990; Moje, 1995; Roth, 1996) shape what counts as (Heap, 1991) science, as well as defining the epistemic knowledge students can develop through such discourses (Kelly, 2008, 2016). Thus, classroom science discourse constitutes a curriculum of science-in-the-making (Kelly, Chen, & Crawford, 1998).