Sink or Float?

Help your child to wonder about and investigate (to learn) things by making predictions (guessing) and observing (seeing what actually happens).

For this Activity you will need:

  • Plastic tub (or bathtub)
  • Water
  • Four (4) to five (five) objects (cork, wood, shell, Styrofoam)
  • Sink/Float Chart (piece of laminated paper labeled "sink" and "float")
  1. Fill the tub with water.
  2. Show your child all of the objects.
  3. Hand your child each object and talk with her about it, ask: What is this? What is it made of? What do you think will happen if we put it in the water? Do you think it will sink (drop to the bottom of the tub) or float (stay on top of the water) in water?
  4. Test out your child’s guess. Ask your child place it into the water to see if it sinks or floats.
  5. Ask your child: "Why do you think it did that?"
  6. Help your child place the item in the appropriate side of the sink/float chart. (For example, the shell should be placed on the "Sink" side of the sink/float chart.)
  7. Repeat the steps with each object.

Next Steps/Follow-Up:
  • Help your child gather other items and make predictions about whether they will sink or float.
  • When giving your child a bath, fill a small plastic bottle with water. Ask your child whether the bottle will sink or float. Test out his guess by putting the bottle in the water. Now pour some of the shampoo out of the bottle. Ask again, "Will the bottle sink or float?" Test out his guess by putting the bottle in the water. Now pour all the shampoo out of the bottle. Ask again, "Will the bottle sink or float?" Test out his guess by putting the bottle in the water. Be sure to ask your child why he thinks the item first sank, then floated.

Background Information:

Scientific thinking involves:

  • Wondering about things.
  • Asking questions.
  • Making predictions (telling what might happen).
  • Looking, listening, touching, smelling, and tasting to get information.
  • Organizing information and talking about it.
  • Comparing things by talking about how they are alike and different.
  • Using words to explain why something happened.

When your child starts school, she will be more likely to do well if she is able to do these things.


You can help build your child’s scientific thinking skills by doing this activity.

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