This paper describes a complex experience carried out with a group of 43 future teachers, in order to encourage them in using technological tools in structural way in education. A didactic proposal, previously tested with 78 High School students, was presented to the trainees, involving them in an experience of meaningful use of technological tools for Mathematics teaching. Continuing a research trend in using technology for Geometry teaching with special attention for the contents, an unusual subject of Elementary Geometry is treated using DGS, aiming at exciting students’ interest and at deepening geometrical concepts. The subject links geometrical and numerical aspects. The methodology involves the students in practical activities for carrying out a sort of ‘analogic computer’.
