Rubber Egg
Egg feels rubbery and can bounce slightly.
Teaching & key ideas
What you do: Bounce prepared de-shelled egg gently from low height.
What students see: Egg feels rubbery and can bounce slightly.
Why it works: Acid dissolves calcium carbonate shell, leaving flexible membrane.
Question to ask: Where did the hard shell go?
Lesson flow
Predict → demonstrate → observe → briefly explain → ask: Where did the hard shell go?