This text outlines the theoretical framework of our study on spatial drawing in the context of primary school. We investigate how children graphically represent a single spatial body. This is one of three conceptual aspects of children’s spatial drawing, the others concern spatial relationships between objects and the overall spatial organization of the image. The planar depiction of a cuboid in the form of a box is a general representational problem for which various solutions are taught and practiced in our culture. From the position of a structure-genetic epistemology, we are interested in children’s process of problem solving, as it emerges in individual and video-recorded case studies - adaptively and intuitively accompanied by the teacher. We reconstruct these processes in detail by using a micro-genetic methodology. With an exemplar we show empirically, how we apply the concept of "well-formedness" to describe the structural orientation towards a “Gestalt” as well as the implicit use of generative systems of spatial representation.