This paper concerns the functions of communication in the mathematics classes. First I show the multiple contexts which exist in the mathematics classes. They consist of the social norms, the sociomathematical norms, the social contexts with respect to the mathematical activities, and the contexts regarding the mathematical contents. And then I place the mathematical communication with respect to these multiple contexts. Second I introduce the communal context and the participants' context in the discussion activity. This framework is used effectively to consider the interaction at the discussion stages. I present two cases of the discussion stages in elementary schools. The first case is discussed for the forming of the communal context, which is necessary for the participants' to provide a solution. The second case is discussed to identify each participants' own context with regards to the communal context. According to these, I show the functions of communication in the mathematics classes as the cultural spaces.
