This article explores relationships between designing and making in the work of children within the age range 5-11 when engaged in practical modelling tasks. The notion of the model is explored from the perspective of concrete representations. It is suggested that concrete models may be used as hypotheses from which to test ideas about the nature of the world. From this perspective, models may be seen to provide crucial platforms for learning. A wide range of sources has informed the article, and these embrace ideas on Hypothesis Theory drawn from linguistic research, as well as historical sources which trace the evolution and development of stimuli for model-making activity. A creative basis for modelling is explored such that a conclusion is reached in which design is seen as an expression of the modelling of possibilities.The concept of the model may be complex and can be seen within a range of contexts. For the purposes of this article, the model is seen as a form of representation. This is consistent with the view of Archer (1992a) who refers to the model as ..anything which represents anything else for informational, experimental, evaluative or communication purposes. (Archer, 1992a, p. 7)As an overarching idea, representations have many modes of expression. An example of this can be seen in language. Text may be viewed as a representation of the spoken word. It may be reduced to symbols and stylised but it has far-reaching powers since the written word can reach out beyond mere vocalisation. It persists. It can be shared and it may be carried across space and time. A range of disciplines beyond design and technology activity can be noted with regard to their use of modelling. Both mathematics and science utilise various forms of representation to model various sequences and systems.Given the representational core of the model, it is hardly surprising that it has a special relationship with designing and making. In the primary classroom, the child will often be engaged in tasks which involve a product outcome. The process of modelling will allow the child to represent a product through a range of measures. The child, for example, may simply talk to peers about a design idea. This act of verbal modelling allows the communication of aspects of a mode of representation, within the limits of language itself. The development of a dedicated vocabulary in design and technology naturally assists this process.The child may represent an idea by a sketch. This gives the representation an air of permanence. It has gone far beyond the limitations of a speech event. The two dimensional representation available on the plane surface of paper presents a fresh challenge, and modelling forms may simply be based on plan and elevation based graphic treatments, or three-dimensional approaches.Then there are built forms. These can offer the potential for a representation to be produced in three dimensions and, as such, allow the practical exploration of space. A range of materials can be used, and indeed assessed for their suitab...