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Sink or Float?

Test out different objects—do they sink or float?


  • water table, large tub, or plastic wading pool (if outside)
  • two plastic bins labeled with picture signs: “Float” and “Sink”
  • various objects that float or sink (for example: rubber bands, sponges, pencils, plastic bottles with tops, wooden blocks, plastic straws, craft sticks, small plastic toys)

Key Science Concepts

  • Objects behave differently in water. Some float; some don’t.


Encourage children to use the words sinking and floating, and science process words such as observe, notice, compare, same, different, change, test, and predict.


  1. Gather children around the water table, tub, or pool. Put objects that sink and objects that float in a bag. Have a child reach in to get an object. Ask:
    • What do you have?
    • What do you think will happen when we put it in the water?
  1. Have each child try it out. Ask children to share what they noticed.
  2. Point out the picture signs on the plastic bins: “Float” and “Sink.” Have children take their object out of the water and put it in the right bin.

Reflect and Share

Try putting several objects in the water at one time and let children compare the ways they behave.

  • Do all the objects float the same way or do some float differently? Describe what they do.
  • Did all the things sink to the bottom in the same way? How were they different? Which sank right away? Which sank more slowly?
  • Ask the children, I wonder what would happen if you pushed something that floated to the bottom? What do you think would happen? Let’s try it.


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