Potential dividers are great and everything by when we put a sensor in there they genuinely become exciting. You need to know how a LDR and thermistor (NTC) work and then what they do to the circuit. The exam questions all boil down to this thing is changing where is the voltage increasing/decreasing in the circuit.
http://en.wikibooks.org/wiki/A-level_Physics_(Advancing_Physics)/Sensors
Year12 Physics 