The Incredible Floating Egg

A chickenThe incredible floating egg is another lesson in density and buoyancy.

What You Need:

Instructions:

  1. Fill the glass with water (leave enough room so that it won’t spill when the egg is added and when stirring takes place).
  2. Add the egg to the water.
  3. Make note of what happens (the egg will sink).
  4. Explain that you are going to add some salt to the water. Ask the children to estimate how much salt it will take to “hold up” the egg.
  5. Add salt, one teaspoon full at a time, stirring after each addition.
  6. Place the egg in the water after each addition of salt to see if it floats.
  7. Record your findings. The egg will eventually float.

How it works:

Eggs are denser than fresh water, so they sink. Adding salt to water increases its density by squeezing more molecules into it. This is why a cup of saltwater will weigh more than a cup of fresh water even though they take up the same amount of room. If you add enough salt, the water will become denser than the egg, and the egg will float.