The Khan Academy is a not-for-profit organisation that aims to provide a high quality education to anyone, anywhere. They do this through a free online collection of video tutorials, practice exercises and assessments. Along with an extensive library of mathematics and science resources (have a look – we haven’t seen so many video resources in the one place!), they also cover history, art history, finance, astronomy, economics, cosmology and computer science.
The Khan Academy is also accessible in the iTunes Store.