Have you ever made salad dressing at home with olive oil and vinegar? Isn’t it annoying when the layers separate and you have to keep shaking it to get a good ratio on your romaine? That happens because of density!

Density is a fancy term for the amount of matter in a certain amount of space, or the mass of an object divided by its volume, like this:

density = mass/ volume

So in that salad dressing example, the oil is less dense than the vinegar, or it has less mass per unit of volume. That’s why it sits on top.

In this experiment, you’ll get to use liquids of all different densities to create a beautiful rainbow in a glass. You won’t want to put this concoction on your salad, though– it includes dish soap and rubbing alcohol, and last I checked, those ingredients are not fit for consumption.

Wonderama Rules:  Safety first. Wear safety glasses and alway ask permission and be supervised by an adult when conducting an experiment.

You’ll need:

  • Clear plastic cup
  • Honey
  • Dish soap
  • Water colored with a few drops of red food dye
  • Rubbing alcohol with a few drops of green food dye


  1. Pour the liquids, to about one inch of height each, into the cup in order from most dense to least dense:
    1. First, pour in the honey.
    2. Next, add the dish soap.
    3. Then add the water.
    4. Then add the vegetable oil.
    5. Finally, add the rubbing alcohol.
  2. The longer you let the cup sit untouched, the sharper and more definitive the boundaries between the layers will become.

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