In vocational education students are to be prepared to participate in communities of practice. Hence they need technical skills as well as content knowledge e.g. science and mathematics. Research has shown that the instructional strategy of guided co-construction may lead to deeper understandings within a practice. The research questions in this article aim at finding out whether guided co-construction is an effective strategy in joining experience and general knowledge with representations as tools for communication and orientation. The present study is a qualitative analysis of a design-based research project. Our goal was to establish how the use of representations developed within a process of tandem tricycle construction. We looked for video data that could potentially explain how representations were used in practice and how such use was related to vocational and academic disciplines. Interesting differences could be revealed which were clearly related to differences in the way representations were designed and used in the whole cycle of problem solving (the construction of a technical object). At two of the four schools the representations remained visible and continued to be used until the end of the process. Designing and using representations as a core activity in vocational education could be the key to integrate theory in designing and constructing in the workshop.