Sketching and design sketches are often recognized as key elements of successful interaction design practice and a central skill in interaction design expertise. Interaction design is a relatively young field without well-developed conventions, tools, and formalisms. We analyze the practical work and the conduct of interaction designers in how they express interaction and dynamics through whiteboard drawings. We focus on how talk and action were used to shape the meaning of the drawings. The ways the designers imagined that users would interact with the system and how it would mediate communication between users became topical through a web of drawings, talk, and embodied action. Our analysis forefronts three aspects of interaction design: 1) the role of the design material 2) the role of embodied action in interaction design, and 3) talk and embodied action as central means of doing design. We argue that the qualities of a design material need to be understood in relation to the activity in which it is taken into use and through the kinds of actions that the participants engage in. This implies that design representations do not carry meaning in themselves but are made meaningful through design activity.