Abstract: This paper examines a research study to foster mathematical discourse about data representations among Indonesian students. It was situated in the context of implementing an Indonesian version of Realistic Mathematics Education, labelled as PMRI, in primary schools. A case study of one lesson involving Grade 6 students on the choice of data representations in Yogyakarta will be discussed. The analysis focused on the enacted social norms and sociomathematical norms during a wholeclass discussion and their impacts on students’ knowledge of data representations. The need for constant effort to enact these norms in classroom mathematical discourse is highlighted.

Key words: Discourse; Reasoning; Communication; Data representation; PMRI