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.

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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. If the molecules are loose enough, air can get through, and the item will float.

The way an item is shaped can also cause an item to sink or float. Here’s an illustration. You can download and print a copy of this with the link below.

Setting Up Your 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 (an apple, 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

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

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 even want to introduce your preschooler to icebergs.

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.

• 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

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

Does your little one LOVE science? Be sure to check out these science topics to feed that love of learning in your little one:

• Living and Nonliving Things
• Preschool Bird Activities
• Creative Preschool Frog Activities