Hot and Cold Water Convection
One arrangement stays layered; the other mixes dramatically.
Teaching & key ideas
What you do: Stack containers carefully hot-over-cold, then cold-over-hot.
What students see: One arrangement stays layered; the other mixes dramatically.
Why it works: Warm water is less dense and rises while cold water sinks.
Question to ask: Which arrangement is stable?
Lesson flow
Predict → demonstrate → observe → briefly explain → ask: Which arrangement is stable?