This theory sees children as needing to actively engage with mathematics, posing as well as solving problems, discussing the mathematics embedded in their own lives and anvironments (ethnomathematics) as well as broader social contexts. Learner (and teacher) conceptions and assumptions need to be articulated, confronted with other perspectives, and challenged, to allow the development of critical thinking. This leads to conflict, which is necessary for the accommodation and growth of new conceptions.