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Density is all about how much “stuff” is packed into a space. A golf ball feels heavier than a ping pong ball because it’s more dense—it has more mass in the same amount of space. The same thing happens with liquids: heavier (more dense) liquids sink, and lighter ones float on top. That’s how you can stack them into a cool-looking tower!

In this project created by Maddie, a member of the Rosie Innovators STEM program for young women in high school, you’ll explore the concept of density by layering different liquids and seeing how they interact. Ready to build your own colorful density tower? Grab the materials and follow the steps below!

Required Materials

  • plastic bottle
  • 2 food coloring
  • dish soap
  • water
  • Vegetable Oil
  • Vegetable Glycerin

Step-By-Step Instructions

Step 1

Grab a bottle and open the cap.You will be adding equal amounts four different liquids to the bottle. Depending on the size of your bottle you will want to adjust the amount added.

Step 2

Add one drop of purple food coloring to your vegetable glycerin. Add the purple glycerin to your bottle.

Step 3

Next add the blue liquid (dish soap) to the bottle

Step 4

Next add one drop of green food coloring to your water. Add the green water to your bottle.

Step 5

Next add the yellow liquid (canola oil) to the bottle.

Step 6

Screw the cap on tight and enjoy the project! Bonus: Place your finished project into the flashlight of a phone and see the colored layers even better!

Real Women in STEM

Resource 1

Dorothy Crowfoot Hodgkin

Dorothy Crowfoot Hodgkin was a chemist who used machines to look inside of crystals and see how atoms are arranged. Her work allowed for other scientists to understand the concept of density and progress the creations of new medicines.