Upside-Down Water Cup

1. Upside-Down Water Cup Materials: Plastic cup; water; index card; tray What you do: Cover a full cup with a card, invert it, then release the card. What students see: The water stays in the upside-down cup. Question: What is holding the card up? 2. Cartesian Diver Materials: Clear squeeze bottle; water; tuned eyedropper/diver What you do: Squeeze bottle to make diver sink; release to make it rise. What students see: The diver obeys pressure from outside the bottle. Question: How can squeezing the bottle move something inside? 3. Blow Between Two Cans Materials: 2 empty cans; 2 pencils/straw rollers What you do: Place cans close together and blow through the gap. What students see: Cans move toward each other instead of apart. Question: Why didn't the air push them apart?

Predict → observe three demonstrations → compare what changed → choose independent activity station → cleanup/share. Guiding questions: Question: What is holding the card up? Question: How can squeezing the bottle move something inside? Question: Why didn't the air push them apart?