Cos’è un quadrato? Figure, teoria e metateoria nell’apprendimento della geometria elementare

A crucial problem in teaching and learning Geometry is the transition from figural aspects to a theoretical approach. Didactical activities in an ‘unusual geometry’, as the spherical geometry, have the potentiality to create cognitive conflicts related to figural components of geometrical entities and can favour the necessity of a theoretical approach, promoting a theoretical and a meta-theoretical thinking.