GNU Operating System Supported by the Free Software Foundation
A program to design and manipulate interactive geometric sketches. It helps kids to explore geometry.
Dr. Geo aims to be an open, easy to study, modify and extend interactive geometry software. It is distributed with its source code. You can modify its own source code while using it. Ten years old kids use Dr. Geo to explore Euclidean geometric sketches; agile kids extend and program it with its embedded dynamic Smalltalk language and user interface.