This chapter focuses on the important role that talk can play in enabling children to develop a deep conceptual understanding of mathematics. The national curriculum for mathematics reflects the importance of spoken language in pupils' development across the whole curriculum – cognitively, socially and linguistically. The quality and variety of language that pupils hear and speak are key factors in developing their mathematical vocabulary and presenting a mathematical justification, argument or proof. Talk is used to explain the structures within mathematics, whereas other approaches use it as a 'mediating tool for meaning-making through the negotiation of ideas'. Research into the effectiveness of different types of talk identifies the following three broad categories: disputational talk, Cumulative talk and exploratory talk. Children should come to appreciate that mathematics is a creative subject who offers a range of approaches to solving problems, rather than a more closed, procedural subject.