Transforming images in a DGS: The semiotic potential of the dragging tool for introducing the notion of conditional statement

Abstract

The advent of dynamic geometry systems (DGSs) has dramatically changed the possible scenario of geometrical experiences at school. The transition from the traditional graphic environment based on paper and pencil, to the virtual graphic environment based on figures on the screen, realized by graphical tools and transformed by acting through the mouse, has the potential of deeply affecting the way students conceive and reason upon geometrical figures.