The practical epistemology used by students and the epistemological moves delivered by teachers in conversations with students are analyzed in order to understand how teaching activities interplay with the "how" and the "what" of students' learning. The purpose is to develop an approach for analyzing the process of privileging in students' meaning making and how individual and situational aspects of classroom discourse interact in this process. Here we especially focus on the experiences of students and the encounter with the teacher. The analyses also demonstrate that a study of teaching and learning activities can shed light on which role epistemology has for students' meaning making, for teaching and for the interplay between these activities. The methodological approach used is an elaboration a sociocultural perspective on learning, pragmatism, and the work of Wittgenstein. The empirical material consists of recordings made in science classes in two Swedish compulsory schools.