The articulation of practice and theory is a central problematic in a dual apprenticeship system that combines working in a company and attending courses at school. Design problems are proposed by teachers as a way to address theoretical concepts in a practical context. The difficulties encountered by apprentices while creating paper based sketches motivated the development of a tabletop warehouse simulation providing apprentices with a Tangible User Interface in the form of a small-scale model. We compare drawings and tangible representational modalities with regards to three phases of design problem solving. Tinkering with tangibles is described as an easy way to engage into the problem. The physical properties of tangibles facilitate the extraction of features relevant for verification. The limited expressiveness of tangibles allows apprentices to focus on the search for a solution rather than on the representation of the problem space.