Roll-Back Can

1. Roll-Back Can Materials: Roll-back can toy What you do: Roll it away across the floor/table and let go. What students see: It slows, stops, and rolls back by itself. Question: Where did the can get the energy to come back? 2. Double Cone Rolls 'Uphill' Materials: Double cone + diverging rails What you do: Release the cone at the narrow end of rails that appear to rise. What students see: It seems to roll uphill. Question: Is the middle of the cone going up or down? 3. Balancing Butterfly Materials: Paper/card butterfly + 2 large washers/clips What you do: Balance the butterfly by its nose on a finger or stand. What students see: A wide, heavy-looking shape balances on a tiny point. Question: Why doesn't it fall?

Predict → observe three demonstrations → compare what changed → choose independent activity station → cleanup/share. Guiding questions: Question: Where did the can get the energy to come back? Question: Is the middle of the cone going up or down? Question: Why doesn't it fall?