Geogebra

Geogebra is an interactive application written in Java and specially used in middle schools as a dynamic way of learning geometry and algebra.

With this educative program teachers and students will simplify all operations. It splits its interface in two windows: one for algebra and another one for geometry.

From the geometry window, you will be able to build constructions using vectors, lines, points, conic sections, segments, polygons or functions that can be dynamically modified.  

On the other side, you can enter or modify elements and equations either through the command line or directly on the screen.

Geogebra will automatically transform operations in a window into the format of the other window. For instance, if you draw a curve its corresponding equation is instantly created on the other window.