The basics quicly summarized:
U = R * I (U is Voltage, R is ohm or Resistance, I is the electricity or Ampers)
P = U * I (P is the effect or Wattage)
This are the most important things to know in electronics, everything else is built upon this. I know your books will say this, but why I'm telling you is that this is SO important, that you should tattoo it to your arm. Also if you don't know enough math to change these formulas (example; U = R * I => I = R / U && P = U^2 / R) then your screwed and should get math classes, and preferably you should have an understanding about cosinus, sinus, and tangens, they are really useful when dealing with alternating currents.
Next step is getting a basic understanding of which component does what,
Basic components are: Resistors, Capacitors, Diodes, Transistors. Look them up, and see what they do when you put power to them and stuff.
Next, to understand IC's (Integrated
Chinese Circuits) you need to learn what logic gates does.
Gates like NOR, NAND, OR, AND, INVERSE, and others.
This will should teach you a great deal of the theoretical basics, further reading recommended. And do buy, and learn to use a soldering iron. The once with regulator for heat and exchangeable tips are highly recommended when soldering inside expensive electronics, like the PS3, PS2, PSP, Wii, and so on
