It is a great challenge for design students to learn to work with interaction and interactive technology. They need to learn about interactive prototypes, to work in teams as well as many other things, and within a limited time. In this paper we identify challenges related to maintaining a shared understanding of concept and implementation and propose a technique to keep teams aligned in the process. Existing conceptualisation tools, such as scenarios and storyboards provide little help to plan to code the control flow and algorithms for sensing the user and effecting feedback. User-friendly coding tools and technology as well as many online example projects are available for students to experiment with interactive behaviour. They are encouraged to jump in at the deep end, puzzling together existing code pieces without any planning. As a result, we found that students resort to trial and error problem solving. This often leaves them with spaghetti code which makes it difficult to understand and improve the quality of the interactive behaviour in subsequent design iterations. Typically, student teams divide who is working on the concept and who is dealing with the code. The Acting Machine technique combines the language of State Machines with enacting techniques, and allows designers to first define and run through interaction scenarios using a visual representation that expresses the core design concept, allows for engagement of the whole team, and has a straightforward connection to implemented code. In this paper we describe the technique and discuss our experiences with it in MSc courses on Interaction Design.