Talk between students and their teachers is central to learning at school, yet students' competence is often understood as the outcome of instructional talk rather than essential to successful participation in instructional talk. Curriculum frameworks used to attribute students with levels of competence reflect these understandings. This article employs Conversation Analysis to consider student'teacher interaction during an independent writing lesson. Discussion of their interaction establishes the link between the student's taken-for-granted knowledge of teacher talk and the teacher's instruction. The finding suggests the importance of locating students' competence within the contextof instructional talk between teachers and students.