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Sink or Float Science

Sink or Float

Ages: 4 - 10

What are some things that sink? What are some things that float?
Experiment, observe, and explore!

Find a spot where you can make a wet mess.
Gather your materials. Go!



  • A button
  • A pencil
  • A marble
  • A metal spoon
  • A plastic fork
  • A sponge
  • A toothpick
  • A small rock
  • A metal bottle cap
  • Anything else you want to experiment with

Testing Data Sheet or Blank Testing Data Sheet (print these out or make your own versions!)


  1. Find a spot (inside or outside) where you can make a wet mess. 
  2. Fill a small container with water (use a clear container if you have one) or fill the kitchen sink half-way with water and use a chair or stool so you can comfortably reach the sink
  3. Collect objects from around your house (see above list for suggestions)
  4. Look at the materials you will be testing and guess which objects will sink or float. Why did you make that guess?
  5. Place the objects in the water one at a time. What happens? Which items sink and which items float?
  6. After observing each item, physically sort them into two piles based on whether the items sink or float. Or record your data by writing or drawing a picture of the object on pieces of paper labeled “Sink” and “Float”. You can use the Testing Data Sheet to record your predictions and results.
  7. Do you notice anything that is similar about the things that float? What about the things that sink?
  8. Keep Exploring! Can you change the features of some of the objects to change the results? Use a rubber band and attach some of the items that sink to items that float. Now what happens?

You can also download and print:

Sink and Float Activity Directions and Helpful Hints (English PDF)

Sink and Float Activity Directions and Helpful Hints (Spanish PDF)


Tips for Supporting Your Children's Learning

Get your child actively involved in their own learning and have their questions drive their learning. Let them observe and figure it out, and try to hold back from answering questions for them. Instead, try to ask: What do we know? What else can we find out? How might we figure that out? Don't be afraid to ask your child questions. Also, don't be afraid to say, "I don't know--let's find out together!" as a way to respond to their questions.

More Activities

Want to learn more about how Frisbees fly?

More hands-on activities and learning opportunities:

Cambridge Public Schools Virtual Enrichment Recommendations

Science Club for Girls at Home recommendation

Other recommended connections

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