According to situated cognition theory, cognitive accomplishments rely in part on structures and processes outside the individual. This article argues that interactional structures - particularly those created through language use - can make essential contributions to situated cognition in rational academic discourse. Most cognitive accomplishments rely in part on language, and language in use always has both representational and interactional functions. The article analyzes one classroom conversation, in order to illustrate how the interactional functions of speech can facilitate the cognitive accomplishments speakers make through that speech. By showing how closely cognition and interaction can interrelate, the article both supports theories of situated cognition and shows how cognition in at least some educational contexts cannot be extricated from enduring social structures and the construction of social identity.