In this study the authors have looked at the use of interactive whiteboards (IWBs) in Mexico from a linguistic anthropological perspective. Twenty lessons were video recorded to compare the use of IWBs and traditional boards in different areas of the curriculum in primary schools. Data were analysed as a set of sequenced communicative events in which participants construct knowledge together in a multimodal environment. The authors found, firstly, that teachers ask students--through the use of language and gestures--to show in sequence their understanding of the use of multimodal objects according to the goals set for the lesson and the knowledge privileged by an academic discipline. Secondly, pedagogic ideologies are an important aspect of students' socialisation into disciplinary knowledge that is embodied in communicative practices. Implications from the research include recognising the communicative competence of participants for achieving joint collective goals, as well as suggesting the design of new participation frameworks with pertinent and creative problem-solving activities for promoting knowledge construction through talk in interaction. (Contains 4 tables and 11 figures.)