Thermostat Bimetal Snap
Metal device moves suddenly by itself.
Teaching & key ideas
What you do: Warm element until it bends/snaps; cool it.
What students see: Metal device moves suddenly by itself.
Why it works: Different bonded metals expand at different rates, building stress until geometry changes.
Question to ask: How can temperature become a mechanical switch?
Lesson flow
Predict → demonstrate → observe → briefly explain → ask: How can temperature become a mechanical switch?