Kojo is an open source App that runs on Linux, Windows, and the Mac. It is a Learning Environment - with many different features that enable play, exploration, creation, and learning in the areas of:

Computer Programming
Math and Science
Systematic and Computational Thinking
Art, Music, and Creative Thinking
Computer and Internet Literacy
To play with Kojo, you can Download and Install it. Or you can run it Online.

The Kojo Overview Story tells you more about Kojo (you need to have Java 6 or later installed to view the Story).

The Kalpana Center Page describes the thinking behind the use of Kojo in Education.

http://www.kogics.net/kojo