if i have a potentiometer acting as a rhetostat, I know I connect an outside pin and the middle pin. Does it matter whether I connect the 5V to the middle pin and the GND to the outside pin, vs 5V to the outside pin and GND to the middle pin?

A "potentiometer" only provides a voltage "potential" if wired +5v, potential, ground. Otherwise, with only two wires connected, you are really providing a variable resistance.

@rdtsc Isn't that what they meant by "acting as a rheostat"?

@barlop Why do you need a variable resistance connected between a fixed positive voltage and ground?

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It turns out gigasample per second ADCs are not particularly cheap.

@ThePhoton I guess I meant the + and the - (respectively) rather than the 5V and the GND