> You you mean stuff like if you put power through a wire, it heats up, and 
> resistance varies by temperature?

Yes pretty much, now imagine that in your design the resistance of the wire 
changes enough to have a big impact on how your circuit works.  If you 
connect an LED to a voltage source and gradually turn up the voltage from 0 
volts, you will see that almost no current flows, it's like nothing was 
connected inside.  But suddenly, you will get to around 2V or something the 
current will shoot upwards, and from then on you only need make tiny 
increments to the voltage and the current will keep getting larger and 
larger very quickly until the LED blows haha

> Oh thank God for that! At least something about my understanding of 
> electricity is correct...

Recipe for solving circuits with resistors:
1) Label each unknown voltage node as V1, V2, etc
2) Write out Ohm's law for each resistor in terms of V1, V2 etc
3) Solve the set of equations you wrote out in 2) for the unknown voltages

> The whole "electricity chooses the easiest path" makes it sound like when 
> an easier path becomes available, all the current goes down that and 
> ignores the other paths! o_O

If the "easiest" path is of *much* lower resistance than the others, then 
yeh you can usually ignore the others.

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