Hot and Cold Water Convection

1. Hot and Cold Water Convection Materials: Two clear containers; hot and cold colored water; cards What you do: Stack containers carefully hot-over-cold, then cold-over-hot. What students see: One arrangement stays layered; the other mixes dramatically. Question: Which arrangement is stable? 2. Bubble Film in a Cube Materials: Wire/straw cube frame; bubble solution What you do: Dip cube frame in solution. What students see: Flat films form surprising interior shapes. Question: Why don't the films simply copy the cube walls? 3. Bubble Inside a Bubble Materials: Bubble solution; straw; tray What you do: Blow one bubble on tray, then carefully blow a second inside it. What students see: A bubble can exist inside another bubble. Question: Why don't the two bubbles instantly merge?

Predict → observe three demonstrations → compare what changed → choose independent activity station → cleanup/share. Guiding questions: Question: Which arrangement is stable? Question: Why don't the films simply copy the cube walls? Question: Why don't the two bubbles instantly merge?