Magdeburg Suction Discs
They can be very difficult to separate.
Teaching & key ideas
What you do: Press cups together and invite a controlled pull apart.
What students see: They can be very difficult to separate.
Why it works: Air is squeezed out and outside air pressure pushes the cups together.
Question to ask: What is pushing the cups together?
Lesson flow
Predict → demonstrate → observe → briefly explain → ask: What is pushing the cups together?