Saltwater vs. Freshwater Density Experiment!


  • 3 clear plastic/glass cups
  • Salt (normal table salt will do fine)
  • Spoons to stir
  • Labels to clearly label cups
  • Small plastic jewels or other small, lightweight objects

Directions: Fill each of the cups up with water. Then, label them “freshwater”, “saltwater”, and “half salt half fresh”. In the freshwater cup, do not pour in any salt. In the half salt cup, pour about 1/2 a spoon of salt and stir to dissolve it. Then, pour a spoon of salt into the container labelled saltwater. Stir to dissolve. If necessary, add more salt so that some of the salt is also settling at the bottom of the cup. Then, drop your small plastic items inside of each up.

You should notice the plastic jewels to sink in the freshwater, but start to float in the salty water. This is because of differences in density. The saltwater is more dense than the freshwater, so the items will float.