Mink Hollow Farm

ECS - Grade 4

10 minutes

• fresh egg(s)
• two glasses of plain water
• salt
• measuring spoon

Try floating an egg in each glass of water. What happens? Now add 1 teaspoon of salt to one glass of water and stir. Add more salt. Repeat until the egg floats. Tally how many spoons of salt were needed to float the egg. What is happening to make the egg float?

When you add salt to the water, you make it heavier, or more dense. Eventually, the water solution becomes more dense than the egg, and the egg floats. It's the same reason why we float more easily in the ocean, which is salt water. If you put the salt in the water carefully enough you can make the density of the water equal to the density of the egg. When the densities are the same, the egg should stay pretty much where ever you leave it in the water.