Interactive electronics tutorials

I've recently started my first circuit bending project - a Yamaha DD-20. This may be a little complex for a first project, but it was the first suitable thing I found!
Anyway, my electronics is a little rusty so I've been doing some searching for tutorials to refresh myself.

I found a pretty comprehensive set of online interactive tutorials on various aspects of electronics.
They are pretty good and take you through a wide variety of topics and each section has a little test at the end so you can check you've actually learnt something.