Water Boils in a Syringe

1. Water Boils in a Syringe Materials: Large needle-free syringe; warm water What you do: Seal tip, pull plunger to lower pressure. What students see: Warm—not hot—water begins bubbling/boiling. Question: How can water boil without getting hotter? 2. Marshmallow in a Vacuum Jar Materials: Vacuum food container/hand pump; marshmallow What you do: Pump air out, then let air back in. What students see: Marshmallow expands then shrinks. Question: What is pushing on the marshmallow normally? 3. Air-Pressure Bottle Fountain Materials: Sealed bottle; two tubes/straws; water; squeeze bulb or pressure source What you do: Increase air pressure in bottle. What students see: Water shoots up the outlet tube. Question: What invisible material is pushing the water?

Predict → observe three demonstrations → compare what changed → choose independent activity station → cleanup/share. Guiding questions: Question: How can water boil without getting hotter? Question: What is pushing on the marshmallow normally? Question: What invisible material is pushing the water?