NSF Summer Outreach 2016–Density




Why is the oil floating on top of the water?

Have you ever noticed that whenever you are cooking, oil floats over the water? This occurs because oil is less dense than water. Density is how much mass there is in a certain space. This means that the volume or the quantity of two different things might be the same but their densities are different. For example, a cup of feathers occupies less space than a cup of water because the feathers are less dense than water. We use other liquids in the kitchen, are they more or less dense than water? In this activity you will be able to find out which liquids in your kitchen are more or less dense than water.



  • 4 tablespoons of milk
  • 4 tablespoons of pancake syrup
  • 4 tablespoons of water
  • 4 tablespoons of vegetable oil
  • 4 tablespoons of dish soap
  • clear container, like a glass



  1. Before making the experiment, make a list of how do you think the liquids will rank from less dense to denser.
  2. Add the water to the container.
  3. Add each liquid, one by one, slowly.
  4. Compare the order of the liquids with the list you made at the beginning. Do they match?


Concept to review:

  • Density
  • Volume



  • Try dropping objects into the liquids. Do they all sink? Where do they end up?
  • Try other liquids and find which one is more or less dense than water.
  • Add some salt or sugar, what happens?


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