Research in situated language use emphasizes the close ties between utterances and ongoing practical activity. In particular, interlocutors in conversation use real-world actions not only to get useful things done but also to demonstrate their ideas and show their understandings of one another. These communicative effects of practical action mount a challenge to theoretical models of the interpretation of language in context.
In this talk, I'll look in detail at one case study, Vi Hart's Origami Proof of the Pythagorean Theorem (http://www.youtube.com/watch?v=z6lL83wl31E). We'll see that Hart's folding serves to anchor linguistic demonstratives, resolve linguistic presuppositions, meet linguistic expectations and help visualize important spatial relationships. These connections explain, in part, how Hart's actions support her utterances, even as her discourse specifies a genuine mathematical proof.