The Next Generation Science Standards (NGSS) strives to shift science learning from the teacher as a single cognitive agent, to a classroom community in which participants are working together in directing the classroom's communal knowledge to figure out questions about how phenomena occur, and building, testing, and refining their ideas to address those questions. To achieve this type of classroom environment, teachers should attend to students' knowledge and ideas and pay attention to how students are located within teacher-led interactions, such as being positioned as active discussants or designated listeners. In this study, we explore if and how this is occurring in the NGSS era. We used a naturalistic inquiry to explore how an experienced first-grade teacher used a new NGSS-aligned unit that called for students to use the science and engineering practices (SEP) to build content knowledge. We used a macro-analytic lens to answer the research question "how are class discussions shaped to address the SEP"? We used a micro-analytic lens to answer the research question "how are students positioned during these science discussions in this classroom?" Evidence suggests that the teachers' whole class discussions incorporated and involved the SEP which were specified in the unit lessons for content learning. However, on a micro-analytic level, we found that few students were positioned as active discussants. The teacher heavily relied on those students who could provide succinct and clearly relevant answers while positioning the remainder of the students as silent spectators. Implications from this research suggest that not only new NGSS curriculum materials need to focus on what students should know and do but they also need to address heuristics for teachers that show them how to position all of their students as active doers of science so all students have opportunities to build deeper, core science knowledge.