Double Cone Rolls 'Uphill'
It seems to roll uphill.
Teaching & key ideas
What you do: Release the cone at the narrow end of rails that appear to rise.
What students see: It seems to roll uphill.
Why it works: Its contact points rise while its center of mass actually moves downward.
Question to ask: Is the middle of the cone going up or down?
Lesson flow
Predict → demonstrate → observe → briefly explain → ask: Is the middle of the cone going up or down?