is concerned with communication in mathematics class-rooms. In a series of empirical studies of project work, we follow students' inquiry cooperation as well as students' obstructions to inquiry cooperation. Both are considered important for a theory of learning mathematics. Special attention is paid to the notions of `dialogue' and `critique'. A central idea is that `dialogue' supports `critical learning of mathematics'. The link between dialogue and critique is developed further by including the notions of `intention' and `reflection'. Thus a theory of learning mathematics is developed which is resonant with critical mathematics education. weiterlesen