Scratch
Free-to-download programming software (models systems and control concepts beautifully.)
Scratch is a new(ish) programming language that makes it easy to create your
own interactive stories, animations, games, music, and art -- and share
your creations on the web.
Fill your head here - http://info.scratch.mit.edu/Educators
This is a brilliant piece of software, developed by clever people at MIT. It can be downloaded to a Mac or PC.
