In my never ending quest to read the internet from beginning to end I found an electronics calculator application that does a nice job of explaining pretty much all of the electronic theory while at the same time, giving you a graphical representation and calculations for things like resistance, capacitance, wavelength, reactance, etc...
http://www.electronics2000.co.uk/If you are having a problem understanding how to calculate resistance or capacitance in series or parallel, how frequency, inductance and capacitance work together or how to read component color codes this may be very helpful.
Tisha Hayes
AA4HA
ARRL VE