Bottle Holes Stop When Capped
Water flow slows/stops when air cannot enter.
Teaching & key ideas
What you do: Let water stream with cap loose, then tighten cap.
What students see: Water flow slows/stops when air cannot enter.
Why it works: Air must replace leaving water; sealed pressure drops inside.
Question to ask: Why does the cap change the holes at the bottom?
Lesson flow
Predict → demonstrate → observe → briefly explain → ask: Why does the cap change the holes at the bottom?