The recent increase in the number of mathematics museums has given rise to a need for tools with which to design and assess mathematics educational proposals in this non-formal context. This study proposes the use of the van Hiele model, a benchmark in mathematics instruction, for the design of interactive museum models focusing on mathematics content in general. By way of example, the model is characterised for application to the Pythagorean theorem. An interactive module designed around the aforementioned characterisation for teaching the theorem at the Museo Didáctico e Interactivo de Ciencias [interactive science instruction museum, MUDIC] may serve as a reference for future interactive modules and workshops in museums dealing with any manner of mathematics content.