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Scientific Prediction and Observation: Sink or Float?

Sweet Pea is 4 years old.

From:  “Sink or Float” is a common activity in Montessori classrooms, but I also found a ton of examples on other blogs : No Time for Flash Cards, The Activity MomSkip To My Lou, and Living Montessori Now.


  • A large clear jar or bowl filled with water.  (We used a beaker from our Primary Science Set.)
  • About 10 small objects.
  • A notebook or piece of notebook paper.
  • A pencil.


  • Tell your tot that she is going to drop each of the small objects into the container of water.
  • Explain that before she drops the objects in the water, she is going to make a prediction about whether she thinks they will sink or float.
  • Help your child create a chart with 3 columns.  1) Item Name  2) The Prediction 3) The Result
  • Write down the name of the first object and ask your tot, “Do you think this is going to sink or float when we drop it in the water?
  • Record her answer in the prediction column.

  • Optionally ask her why she thinks the object will sink or float.
  • Allow her to drop the object in the water.
  • Ask, “So did it sink or float?” and then record her answer on the chart.
  • Repeat with the remaining objects.

Observations: Sweet Pea had a great time with this activity.  She loved discovering if something was going to sink or float.  She did not know why an object sank or floated.  She thought that it had to do with the size of the object and I didn’t correct her, but just let her keep testing the objects to see what happened.  For example she predicted that a raisin would float because it is small, but was amazed when she discovered that it floats instead.

I loved doing this activity with her and it will be interesting to repeat in the future to see how her reasoning develops.

Notes from the Trenches:   If I’d been thinking, I would have saved the cotton ball (which floated and then sank) for later in the experiment, because it was a little confusing to use as our first object.

Rating: 4 Stars * (Fun, Easy, Independent, Frugal)


♥ Linky Love ♥:  I love Mary Ann Johanson ‘s geeky girl take on movies at her Flick Filosopher movie review site.


2 comments to Scientific Prediction and Observation: Sink or Float?

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