GeoGebra

GeoGebra is a free and multi-platform dynamic mathematics software for schools that joins geometry, algebra and calculus.

On one hand, GeoGebra is an interactive geometry system. You can do constructions with points, vectors, segments, lines, conic sections as well as functions and change them dynamically afterwards.

On the other hand, equations and coordinates can be entered directly. Thus, GeoGebra has the ability to deal with variables for numbers, vectors and points, finds derivatives and integrals of functions and offers commands like Root or Extremum.

These two views are characteristic of GeoGebra: an expression in the algebra window corresponds to an object in the geometry window and vice versa.

It received several international awards including the European and German educational software awards.

To discover more about GeoGebra, click on the following links:
GeoGebra Website
GeoGebra Wiki