In mathematics classrooms, body-based actions, including gestures, offer an important way for students to become mathematical ideas as they engage in mathematical practices. In particular, a type of gesture that we call a dynamic depictive gesture allows learners to model and represent fluid transformations of mathematical objects with their bodies. In this paper, we report on two empirical studies – one in which dynamic gestures were observed, and one where these gestures were directed. We conclude that dynamic gestures are a key element in successful justification and proof activities in mathematics
