At-Home Science Experiment: Why Does A Duck Float?

A fun science experiment that uses bath and pool toys explain why ducks float. Best for kids in kindergarten through 2nd grade!

Background:


We’ve seen ducks and other birds float on water. Why do they float? The secret is in the feathers:

• Birds’ feathers are covered in oil, which floats on water. But that’s not the whole answer!
• Because oil and water don’t mix, the natural oil on birds’ feathers helps trap air around birds’ bodies. Air is lighter than water, so all of this extra air also helps birds stay afloat!

Materials:

• Rubber duck (time for those bath toys to come in handy!)
• Bowl of water
• Clear jar or glass
• Vegetable oil
• Feathers (available at a local arts & crafts store)
• Petroleum jelly / Vaseline

Science Experiment:

1. Float the rubber duck in bowl of water. Ask your child to guess why the duck floats on water. (Answer: it’s filled with air!)




2. Explain that there is air all around us – the water isn’t floating out of the bowl, and the air isn’t falling down into the water. This is because air is lighter than water!




3. Show that air floats on water in another way: have your child turn the empty, open jar or glass upside down and push it down into the water. What is happening to the bubbles of air coming out of the jar? (They’re rising to the top!)




4. Ask your child to take a few feathers. Have you ever seen a duck nibble its feathers? What the duck is really doing is nibbling a gland that spreads oil on the feathers. Why would a duck do this? (Answer: Oil and water don’t mix, so this keeps their feathers from getting wet! This way the duck can trap air around its body, and air helps the duck float on water.)




5. Did you know that oil also floats? Let your child explore what happens when oil and water mix by taking the duck out of the water and adding a few drops of oil into the bowl of water.




6. Now, what do you think happens if you cover a feather in oil? Have your child smear Vaseline / petroleum jelly on the feather. (Have paper towels near by to clean hands afterwards.) While your child is busy doing this, replace the bowl of water so that no oil is floating on top. Put the feather on the water to test your theory! (It will float.)




7. What do you think will happen if you put a feather that’s not covered in oil into the water? Try it out! Put the clean feather next to the oil-covered feather. (Once it gets wet, it will sink to the bottom of the bowl.)




8. After the experiment, ask your child whether or not people float on water. How do inner tubes and water wings help us float? Will they float if they’re not filled with air first? We use these water toys the same way that ducks use feathers – to float! (Fun follow-up: head to the pool!)

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