• Container
• Uncooked egg
• Stirrer
• Magic crystals (salt)
• Warm water

This activity makes a good magic trick.

1. Place egg in container.
2. Fill container about ¾ full of warm water.
3. Stir.
4. Announce that you will now make the egg rise.
5. Take a drink of the water to prove that it is just plain water in your container.
6. Add magic crystals (salt) and stir and then watch the egg rise.

• Does the amount of salt needed to make the egg rise change with the size of the egg?
• What happens if you use cold water instead of warm?
• What happens if you use a hard-boiled egg isntead of an uncooked egg?

This trick deals with density (mass per unit volume). A rock is very dense because of all of the billions of molecules that are packed tightly in a small amount of space. Water is not as dense because its molecules are not packed as tightly – there are fewer molecules in the same amount of space.

The egg is more dense then the water, so it sinks. However, when the magic crystals (salt) are added, they dissolve and turn the water into a solution that is more dense than the egg. This is why the egg floats.