Ball-and-Ring Thermal Expansion
A tiny temperature change can stop/start the fit.
Teaching & key ideas
What you do: Show ball fits cold; warm ball or ring as apparatus permits.
What students see: A tiny temperature change can stop/start the fit.
Why it works: Metals expand when heated because average atomic spacing increases.
Question to ask: How can something get bigger without adding material?
Lesson flow
Predict → demonstrate → observe → briefly explain → ask: How can something get bigger without adding material?