A shared tenet of embodied, embedded, situated and distributed cognition is that people make sense of things interactively. They run a simulation, they exchange words, often taking turns to change and steer the flow of interaction; they gesture, they handle or manipulate things, they write, sketch or model. Because the concept of interaction seems intuitive, and the phenomena so pervasive, researchers tend to use the term to do more work than they have time to explain. This symposium explores different ideas about the way interactivity is understood, and how it figures in thought processe