Prosody refers to features of speech such as intonation, volume and pace. In this paper, we examine teacher-student dialogue in an English lesson at a secondary school in England, using Conversation Analysis notation to mark features of prosody. We also make connections with Goffman's theoretical concept of footing. We show that, within an episode of teacher-led plenary discourse, prosody may be used to signal shifts in footing between different kinds of pedagogic activity. We identify: (i) teacher-led IRF (Initiation-Response-Feedback) discussion; (ii) the teacher's modelling of exploratory talk; (iii) a shift to instruction-giving. If teachers are able to model the enquiring tone of exploratory talk, they may in turn encourage more thoughtful contributions from students.