The theory of teaching is inadequate, de-emphasizing the role of the teacher. The teacher has at least three essential roles, which the progressive educator perspective fails to recognize adequately. First, the teacher mediates between the corpus of mathematical knowledge and the learner, involving the selection and representation environment and in planning learning experiences. Secondly, the teacher must monitor children’ s learning and intervene in their sense making, by communicating feedback and managerial instructions to the children, challenging children to reconsider their responses, regulating interaction. Thirdly, the teacher provides a role model for the children through her behavior and social interactions. In each of these ways the teacher is central to the process of education, and insufficient acknowledgement is given to this.