We set out to understand how different instantiations of inquiry emerged in two different years of one elementary teacher's classroom. Longitudinal observations from Mrs. Charles' 5th grade science classroom forced us to carefully and deliberately consider who exactly was responsible for the change in the class activities and norms. We provide empirical evidence to show how a focus on the teacher can easily overlook the complex dynamics of the classroom. The data reveal that students had a substantive and generative role in the class's arrival at the different instantiations of scientific inquiry--the nature and form of inquiry--that were constructed each year. We argue that, in an environment where a teacher carefully attends and responds to student thinking, the nascent resources students have for reasoning about phenomena can affect not only the conceptual ideas that emerge, but also influence what inquiry activities or practices become established as normative and productive over time. Our work with Mrs. Charles illuminates an important methodological concern with research on teacher development as well as the construct of teacher learning progressions; research accounts that focus primarily on the teacher may overlook the classroom norms that are negotiated between teacher and student, and thereby provide an incomplete portrayal of the teacher's activity within one classroom and the teacher's progress across multiple years.