The one I've been playing with currently is running for $6.99 (I bought mine for $9.99). It has a temp range of -33 to 110 degrees C (-27 to 230 Deg.F) so is a little limited and I haven't been able to gauge it's precision yet. Its ease of use and price make up for any of it's shortcomings, however.
Possible Labs or Demos:
- Black absorbs heat more quickly, does it radiate more heat than white?
- Insulators and conductors - Both may be the same temperature, but do they feel the same when you touch them? A piece of Styrofoam and metal fresh from the fridge or freezer would do nicely.
- You can replace melting wax on the ends of conductors with a quantifiable temperature.
- Resistors in a circuit, which ones get the hottest? Why?