Eggs won't float in a plain glass of tap water.

Concepts like density and matter can be hard for many third-graders to understand. Conducting a simple demonstration with everyday household objects like an egg and a pitcher of water can help make these concepts easier to understand. Parents or teachers can conduct this simple science project with their third-graders to help them understand density and apply the concept to other situations.

Fill a clear glass or container with tap water.

Drop the egg in the water and watch to see if it floats. Ask children about why they think it didn't float. Ask them if they think the egg is heavier or the water is heavier, and talk about their answers.

Talk about what could make the water heavier, or denser. Discuss possible solutions, and then introduce the idea of adding salt to the water.

Add salt to the water one tablespoon at a time to see whether the egg will float. Stir the salt to dissolve it each time.

Talk to children about how the salt is making the water denser so that it is heavier than the egg. Explain how when the water is more dense, the egg can float.

Things Needed

  • ['Egg', 'Clear glass or container', 'Water', 'Table salt', 'Tablespoon']


  • Once children have a better understanding of density, talk with them about other common items and whether they think they will float in the water.

    Experiment with floating an egg in other liquids, such as milk or soda.