Come allievi di terza media hanno studiato un collegamento tra gli sviluppi dell'ottaedro e del cubo

In this paper we show the objectives, the articulation andthe results of an activitiy realized whith the pupils of a 3rd grade of middle school (13 years old) concerning the study of the nets of a regular octahedron and the individuation of the links existing between them and the nets of a cube. Such activity, which has offered a good chance to bring the concrete world of the pupils closer to the notion of duality among regular polyhedra, was based on an experiment — carried out the previous year — in which the nets of a cube and of a right parallelepiped with two or three different dimensions were classified. With the former activity, instead, we chose to put the pupils in a situation in which they should operate on the non-right angles (both plane and dyhedron) and observe their reactions and difficulties.