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Build a Bathtub Toy Raft Powered by Surface Tension

by Teisha Rowland, PhD
Active Time
10-20 minutes
Total Project Time
10-20 minutes
Key Concepts
molecules, surface tension, surfactants
Rubber, floating fish with a Styrofoam raft.


Have you ever wondered why a water strider can walk on water? Or how detergent can clean your dishes? If you look around you carefully, you can find dozens of similarly interesting phenomena that are all linked to the surface tension of water. In this science activity, you will make a little toy raft that is actually powered by surface tension, and use your vessel to investigate how surface tension works!


Teisha Rowland, PhD, Science Buddies
This activity is not appropriate for use as a science fair project. Good science fair projects have a stronger focus on controlling variables, taking accurate measurements, and analyzing data. To find a science fair project that is just right for you, browse our library of over 1,150 Science Fair Project Ideas or use the Topic Selection Wizard to get a personalized project recommendation.


  • A small, flat piece of Styrofoam, at least about three inches by three inches. For example, this could be part of a take-out container or a meat packaging tray.
  • A toothpick
  • Kitchen sponge. Use either a fresh sponge or rinse the sponge thoroughly with water to make sure it does not have any soap in it.
  • Liquid dish soap or liquid laundry detergent
  • Water
  • Large basin, sink, or bathtub
  • Scissors
  • Utility knife or X-ACTO knife
  • Optional: Medicine dropper and ruler
    Materials for doing the surface tension raft activity.
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Active Time
10-20 minutes
Total Project Time
10-20 minutes
Key Concepts
molecules, surface tension, surfactants