Casyopée is a free open-source software environment for the learning of functions at secondary school level. It has been designed by a group of teachers and researchers within several projects.

It aims at making numeric, graphic and formal exploration of mathematical functions easier, as well as problem solving.. It gives students specific help in his/her activities, thanks to symbolic computation. Thanks to the four tabs of the interface (algebra, graphics, dynamic geometry and "geometrical calculations", it allows exploring and modelling diverses situations.

Functions can be created and processed from an algorihm, as a model of a dependency in a geometrical figure, as well as by a formula.

With Casyopée, power means neither complexity nor lack of rigor :

- choices of representation are in line with mathematical conventions at secondary level ;
- driving Casyopée is easy, without any command language ;
- the goal is to help the student, not to restrain him/her.