All potentiometers are not created equal, and particularly in the cheaper devices they may not have a consistently matched resistance ... pots together as a Wheatstone bridge.

But we were going to talk about Wheatstone bridges ... You could use two matched resistors in part of the bridge, have an unknown resistance in one of the remaining legs and a variable resistor ...

Wheatstone circuit bridges are electrical bridge circuits that are used to measure resistance. Wheatstone circuit bridges consist of a common electric current source such as a battery and a ...