During the 1980s increasing attention was paid to writing-to-learn elementary school subjects outside of traditional language arts courses. The concept of writing-to-learn in science has much in common with the concept of a science learning community premised upon a social constructivist epistemology. This paper reports on research designed to provide evidence that oral and written discourse can play an important part in student learning of science concepts. The researcher conducted research on her own teaching of 25 fifth-grade students, using a social constructivist epistemology to guide her teaching. Analysis of classroom interactions and interview data revealed that in order for students to participate in a learning community in which there is social construction of science knowledge, there needed to be a change in a number of classroom norms including those for the roles traditionally played by teacher and students, the source of authority for the knowledge learned, and the purpose of and audience for classroom talk and writing. In addition, there needed to be an opportunity for teacher and students to explore genuine questions together as members of a learning community. When a change in these norms took place, students over time were able to use their science knowledge in a flexible manner in multiple contexts across the school year, rather than in one context for purposes of a test and then forgotten. (MDH)