Egg Floats in Salt Water

1. Egg Floats in Salt Water Materials: 2 clear cups; water; salt; egg What you do: Put egg in fresh water then concentrated salt water. What students see: Egg sinks in one and floats in the other. Question: Did the egg change—or the water? 2. Soap-Powered Paper Boat Materials: Paper/foam boat; water; dish soap What you do: Float boat; touch soap at notch in rear. What students see: Boat zips forward. Question: What pushes the boat forward? 3. Hydrophobic Sand Stays Dry Materials: Hydrophobic 'magic sand'; water; clear cup What you do: Pour sand into water, then remove a clump/spoonful. What students see: Sand looks dry even after being underwater. Question: How can something be underwater but not wet?

Predict → observe three demonstrations → compare what changed → choose independent activity station → cleanup/share. Guiding questions: Question: Did the egg change—or the water? Question: What pushes the boat forward? Question: How can something be underwater but not wet?