Interaction and dialogue are seen as essential components of mathematics classrooms of the 21st century. In this paper we explore the pedagogical actions a teacher takes to reposition his diverse learners as active and engaged participants in the classroom. The findings illustrate the need for explicit teacher modelling of ways for students to participate and explain and justify reasoning. We illustrate how teacher actions led to agentic students and a shift from social to sociomathematical norms in the construction of mathematical explanations, justification and generalisations.