Also, it may be worth checking out the walkthrough video and extended docs here, linked from @stchangg's post: http://khan-exercises.readthedocs.org/en/latest/i

Also, it may be worth checking out the walkthrough video and extended docs here, linked from @stchangg's post: http://khan-exercises.readthedocs.org/en/latest/index.html http://khan-exercises.readthedocs.org/en/latest/index.html