Float or Sink?

Let’s turn science into fun. Your kid will love testing everyday objects to see which ones float and which ones sink—it’s simple, hands-on learning that feels like playtime.

You’ll Need:

  • Two bins or large bowls filled with water
  • Labels or cards that display “Float” and “Sink”
  • A mix of objects to test

Things that Float:
› Plastic spoon
› Sponge
› Rubber duck
› Ping pong ball
› Empty plastic bottle (with cap on)
› Cork
› Pool noodle slice
› Foam letters or numbers

Things that Sink:
› Metal spoon
› Small rock
› Big coin
› Key
› Marbles
› Crayon
› Grape or cherry tomato

Let’s Make it:

  1. Fill two bins or bowls with water—label one “Float” and one “Sink.”
  2. Gather your mix of objects and invite your child to make predictions: Will it float or sink?
  3. Drop each object into the water and watch what happens. Sort them into the correct bin and talk about why.

What’s Happening Here?

  • Density is a science word that tells us how heavy or light something is for its size.
  • If an object is light for its size, it means there’s lots of air or empty space inside—like a sponge or a rubber duck. That’s why it floats, because the water can easily hold it up.
  • But if something is heavy for its size, like a rock or a metal key, it’s packed really tightly with no space for air. That’s why it sinks—the water just can’t hold it up.

Why We Love It:

  • Turns simple water play into a hands-on science experiment.
  • Builds observation, prediction and reasoning skills through exploration.
  • Encourages curiosity and conversations about why some things float while others sink.

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