In this paper we will investigate and document some of the practices that a group of children use to form an activity of creating a screen-based interactive play world using a tangible programming system. A specific focus is on the resources that the children use to create and maintain a sense of shared understanding of what they are building. We emphasise the embodied aspects of interaction in the activity and how physical resources and bodily action must be viewed as intrinsically intertwined with the children's process of argumentation and articulation.