Written and Photographed by Julia Furukawa

It’s hard to explain why it’s easier to float in the ocean than in the swimming pool. But this experiment, which only requires an egg, salt, a glass, and water, will illustrate for kids how salt increases the density of water, making it easier to float in. 

  • Fill a large glass with water, leaving about an inch of space at the top 

  • Have your kids place an egg in the water and watch how it sinks 

  • Remove the egg and pour a decent amount of salt into the glass 

  • Have the kids stir until the salt is dissolved 

  • Place the egg back in the glass and watch how it floats. 

  • There you have it — salinity and water density in action!