What is ohms law? Try this circuit!: http://goo.gl/9TkMwY
The key to understanding electronics is to first understand ohms law. giving you the tools to move forward onto more electronics theory.
I = V/R
V = I * R
R = V/I
R = Resistance (ohms)
I = Current (Amps)
V = Volts
EveryCircuit (http://everycircuit.com) was used in this demonstration.