The ability or tendency to float in water or air or some other fluid.

  • The power of a liquid to keep something afloat.

Let’s make some boats out of aluminum foil and test how buoyant they are by adding pennies to the boats until they sink into the water.


  • 2 square pieces of aluminum foil (12″x12″ is recommended.)
  • 1 basin, bowl, bathtub, or a kiddie pool
  • water
  • a bunch of pennies


  1. Create a unique boat with one piece of foil. When designing your boat try to include features you think will help the boat stay afloat the longest and hold the most pennies.
  2. Place your boat in your water and add pennies one by one. Keep count as you add the pennies to the boat.
  3. Make note of how many pennies your first boat was able to hold. Did you notice any points of weakness in the design of the boat?
  4. Take what you learned from your first boat and design a second boat with your last piece of foil. Try to make this boat more buoyant if you can.
  5. Repeat step 2.

  Which one of your boats was more buoyant?

You can download the free companion worksheet for this exercise.