Onion Experiment for Kids

Here’s a simple Onion Experiment for Kids that will not only answer the question ‘Why onions make you cry’ but also help you find ways of taming those tears.

This simple Onion science experiment is perfect for kids of all ages – be it your toddler or your teen. While kids will learn cool science from this activity, adults will get clever tips to avoid tearing up while doing the chopping.

But first let’s understand the science behind onions and the tears.

Why Onions Make You Cry

Onions contain sulphur amino acids. When you cut an onion, you break its cells releasing enzymes which react with the sulphur amino acids present in the onion to form a volatile gaseous compound called propanethiol S-oxide.

This gas is the culprit behind the irritation and stinging in the eyes. But before you think it’s propanethiol S-oxide that causes you to tear up, it’s not! It’s actually your body’s self-defence mechanism that causes you to tear up.

Your amazing body sets into action when propanethiol S-oxide reacts with the moisture in your eyes, irritating them. To flush this irritant gas out of our eyes, your brain triggers a tear response causing your peepers to water.

So it is not really the onion! It is our amazing defence mechanism at play!

Quick Tip: While Onions make you cry, these Silly Science Jokes are sure to set the mood right!

Simply put, without any heavy scientific nomenclature, tears are our body’s way of washing away the sulfur containing gas onions release.

Fun Fact: Tears are produced by Lacrimal Glands located above the eyelids towards the exterior of the eyes.

Wonderful, isn’t it? How a simple process of chopping onions triggers our defense mechanism and has so much science behind it. To explain it to your child, you can omit the name of the gas and simply mention that they release a gas that irritates our eyeballs causing us to tear.

Here is a simple onion experiment that will help your kids (and you!) to find clever ways to avoid the irritant and in turn the tears.

You will need:

Onions
Lab Glasses – swimming glasses work as well!
Boiling Water
Knife
Chopping Board
Observation sheets – garb the free printables at the end of the page

Scenario A: Ask your child to wear lab/swimming glasses and chop an onion. For younger children, ask them to stand next to you while you do the chopping.

Scenario B: Take another onion and place it in the refrigerator and allow it to cool for 10 minutes. Now chop the onion without wearing any eye gear.

Did your eyes water again? If yes, did they water as much as they did while chopping an onion at room temperature?

Scenario C: Take a pan of boiling water and put an onion in it for 10 minutes. Chop it and note your finding.

Wearing lab glasses prevent the gases released while chopping to come in contact with eyes. And hence, eyes to not water in this case.

Temperature also influences the amount of gas released by the onion and thus a cold onion might not make you cry as much.

Discuss your findings with your child and ask her if she can think of more ways to protect the eyes from watering while chopping an onion. You never know you might just discover a new way to avoid onion induced tears!