While you’re in the bath…

Sometimes the simplest experiences embody the most science learning. Children love water play, and they love experimenting with water.

This one is more science than innovation, but making an informed decision and finding out what happens is the very beginning of being able to take a calculated risk – a great skill for innovators and entrepreneurial types. So it makes sense to encourage children to hypothesize and then test, in this case, whether or not any number of objects will sink or float— and to learn some of the science behind the “magic”.  

You’ll need:
• Preschool child who is curious and loves to splish ‘n’ splash
• Tub or basin filled with at least 8” of water
• A paper or fabric bag
• A number of items representing a variety of materials (wood, metal, plastic, aluminum foil, and plastic) such as, plastic bottles, toy blocks, paper, bathtub toys, plastic spoons, rubber balls, plastic bottle caps, crayons, erasers, sponges.
• Paper cups

To do:

Place all the objects into the bag.

While your child watches, shake the bag and chant this silly verse:

Shake, shake, shake
What shall I vote?
Shake, shake, shake
Will it sink or float?

Have your child reach in and select one object from the bag. Have your child then predict if that object will float on the water or sink to the bottom. Repeat until all the objects have been tested and classified as sinking or floating items.

Ask your child if the items that sink and those that float seem to share any characteristics (e.g., size, shape, colour, weight, etc.) in common.

Ask your child for his or her explanation as to why some things float and others sink. No matter what your child’s explanation, say that he or she sounds like a real scientist who thinks about why things happen the way they do. Then, explain that when an object is placed in water it “displaces” or moves a certain amount of water aside.

Explain also that when an object moving the water aside weighs less than the amount of water it replaces, the object will float; if it weighs more than the amount of water it replaces, it will float.

Variation:

To help your child understand that air is everywhere, show your child how turning a plastic cup upside down and then pushing the cup of air straight down into the water. Once the cup reaches the bottom of the basin, show your child how, by tipping the cup slightly, the trapped air can escape in the form of air bubble. Explanation: Water pressure pushes the air out of the cup, replacing it with water.

Sink and Float Discoveries Game download
1 A4 sheet to download and print out (PDF file approx 650KB)

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