Thermostat Bimetal Snap

Metal device moves suddenly by itself. Ask students to predict what will happen. Warm element until it bends/snaps; cool it. Key idea: Different bonded metals expand at different rates, building stress until geometry changes. Ask: How can temperature become a mechanical switch? Safety and cleanup: Teacher handles warm source. https://www.google.com/search?q=%22Thermostat+Bimetal+Snap%22+science+demonstration+experiment