In this paper, I approach the question of what makes a text coherent from a pedagogic perspective. I begin with Halliday and Hasan's (1976) canonical observation that a coherent text must be ‘consistent in register’. I then explore this notion from the perspective of a stratified model of context (as genre and register), focusing on a law lecture text dealing with misrepresentation. Shifts in field, mode and tenor are documented for this text, challenging the idea that a coherent text must in some sense be the 'same' register throughout. I then bridge from recent work in Legitimation Code Theory (its autonomy plane) to propose a revised SFL model of pedagogic discourse. This is used to re-interpret register shifting in the law lecture as shifting in the service of its curriculum genre. I close with discussion of the implications of these observations for modelling context and for respecting lecturing mode as far as its complementary role in teaching/learning is concerned.