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Sink and Float Activities for Preschoolers


Sink and float activities for preschoolers are a great way to introduce science experiments to this age group. With these experiments, you and your child will collect a variety of items and guess (predict) whether the item will sink or float.

Plastic tub filled with water with items that are sinking or floating

Sink and Float Activities for Preschoolers

For preschoolers to have fun with sink and float activities, they don’t need a complicated physics lesson. I have taught this lesson many times and have found a simple explanation will do. They just enjoyed guessing what would sink and what would float and observing the results – and that’s ok. If that’s all your child is interested in, let them have fun with that.

Why Do Some Objects Float While Others Sink?

In case, you have a preschooler who wants a ‘density definition for kids’ of why things float or you just need a quick refresher yourself, here’s a simple explanation:

Everything is made up of molecules. If the molecules are packed too tight air can’t get through and the item sinks. It the molecules are loose enough, air can get thru and the item will float.

The way an item is shaped can also cause an item to sink or float.



Setting Up Your Experiment

items and a container of water for sink and float experiment

To set this up you need:

  1. Something to hold water in like a clear bowl or plastic container. ( This could also be done with an outside water table or even the bathtub)
  2. Items from around the house or outside. Some ideas to try:
    • sponge
    • rubber band (What happens if this is cut? )
    • paperclip (What happens if this is spread out straight?)
    • key
    • pencil
    • feather
    • spoon (try a plastic and metal one)
    • stick
    • leaf
    • stone/ pebble
    • shell
    • Lego ( Do several Legos together make a difference?)
    • block
    • fruit (apples, orange, grape)
    • egg
    • a flat piece of aluminum foil (What happens if it’s squished into a ball?)
  3. For each item, ask your child what they think will happen, then let them place the item in the water. Did it sink or float? Does it make a difference if the item is set in more gently or dropped in harder?

More Sink and Float Activities

Here are a few more easy sink and float science experiments to explore:

1. Sink or Float Apple Experiment

three apples (red, green and yellow)

Does color make a difference? Experiment with different colored apples – red, yellow, and green. Let your child determine if color makes a difference in whether the apple sinks or floats.

2. Ice and Water Experiment

Ice and ice scopper

Have your child predict if ice will sink or float when added to water. Let them drop some into the water and observe what happens. You might want to use this experiment to introduce icebergs. What is an Iceberg is a quick, 2-minute YouTube video you can share with your preschooler if they are interested.

3. Experiment Adding Something to the Water

Experiment with what happens if you add something to the water. Some things you might want to try:

  • salt
  • dish soap
  • syrup
  • cooking oil
  • baking soda

4. Can You Change Something that Sinks?

Here are a few experiments your child can try, to see if you can change something that sinks into something that floats.

water bottles
  • A water bottle.
    • Put a filled water bottle into a container of water. What happens?
    • Empty the bottle, put the lid back on and try again. What happens?
    • What happens if you put the empty water bottle in without the lid on?
    • Does the lid sink or float?
  • Playdough
    • Ball up a chunk of playdough and place it in the water. What happens?
    • Shape a chunk of playdough into a boat. Did the same thing happen?
  • An item on top of an item
    • What happens if you put an item that sinks on top of an item that floats?

Your Child’s Own Ideas

preschool girl smiling

As your child experiments, they will have their own thoughts and questions. Keep them safe but have fun together letting them explore their ideas. That’s what scientists do.😊

Be sure to check out these science topics, to inspire a love of learning in your little one:



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