Importance of semiotic representations: how CAS can help

Mathematics Education research has firmly shown the importance of the semiotic representations and of their relation w.r.t. the cognitive process (Duval, 1993). In this paper we want to show how CAS can improve learning because of the possibilities they offer to represent concepts using various semiotic registers. We start our considerations taking into account some entrance tests for Mathematics Teachers Training School. Some of the given multiple choice questions have been formulated involving more semiotic registers. The given question not only aims to verify the capability of the student to solve systems of inequalities but also his/her capability to pass from a semiotic register to another one