Sink or Float?

Grade: K-1

Young students can make discoveries about the buoyancy of different materials in this hands-on experiment.

Sink or Float
By Janet Wong

Popsicle stick.
Crayon. Straw.
Brand new shiny penny.

I’m guessing which
will float like a boat—
I wonder which will. Any?

Take a guess:
what do you think?
Try it—check if it will sink!


  1. Sink or bathtub

  2. Paper towels or washcloths

  3. Printout of the Sink or Float? table or make your own

  4. A variety of objects that will both sink and float in water, like popsicle sticks, crayons, straws, pennies, corks, metal rings, paper scraps, feathers, buttons, and marbles. Peeled and unpeeled citrus fruits (tangerines, lemons, limes) and eggs are also fun objects to test!


  1. Read poem by Janet Wong

      1. Optional: Have your student gather some objects to test in addition to the ones you have prepared!

  2. Fill up sink or tub with water

  3. Have students guess whether each object will sink or float right before testing it

  4. Have students test each object twice

  5. Record what happens in your table

Questions to Ask:

  1. Which objects floated?

  2. Which objects sank?

  3. Do the objects that floated have anything in common? What were they made of? How were they shaped?

  4. Do the objects that sank have anything in common? What were they made of? How were they shaped?

  5. Why do you think we tested each object twice?

  6. Did your guesses about which objects would sink or float get better?

Expanding the Activity:

  1. Play this interactive Sink or Float game by Houghton Mifflin Company

  1. Watch Elmo help Abby build a boat for her pet rock

  2. Can you turn a sinker into a floater? Using materials from around the house (corks, clay, plastic cups, tin foil, etc.) see if you can engineer something that will keep one of your sinkers afloat.

Activity Source: Modified from Science and Children Magazine, April-May 2019, National Science Teacher Association

Image Source: Andres Victorero from Pexels