Newton's Cradle
Balls on the far side move while the middle balls barely do.
Teaching & key ideas
What you do: Release one ball, then two.
What students see: Balls on the far side move while the middle balls barely do.
Why it works: Momentum and energy transfer through nearly elastic collisions.
Question to ask: How did the last ball know to move?
Lesson flow
Predict → demonstrate → observe → briefly explain → ask: How did the last ball know to move?