Kitchen Science 3-minute video · ages 4-8 · free coloring page
Why does popcorn pop?
A popcorn kernel is small, hard and yellow. But heat it up, and pop! It turns into a big, white, fluffy puff. Why?
3 min
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Free coloring page
The scene from the video as a coloring page, plus the three-sentence answer, the experiment, and a QR code back to this page. One sheet, US Letter, black and white.
The answer in three parts
Why?
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Inside the hard shell there is starch, and a tiny bit of water.
The shell is called the hull. It is strong and tight, with no holes at all.
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Heat turns the water into steam, and steam needs much more room.
It pushes on the shell from the inside, harder and harder, like blowing more and more air into a balloon. The hot steam also makes the starch soft and gooey, like hot jelly.
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Pop! The shell bursts and the steam rushes out.
That is the sound you hear. The soft starch puffs up like foam, cools in a blink, and turns dry and crunchy. The kernel is turned inside out and many times bigger.
For grown-ups: Only popcorn has a hull strong enough to hold the steam until the big pop. Sweet corn has a thin, soft skin, so the steam just leaks out.
From kernel to puff
- Hard kernelstarch + a drop of water
- Hot!water turns to steam
- Pop!shell bursts
- Fluffy puffdry and crunchy
A tiny experiment
Try it!
The spoon test
You need: popcorn kernels, a spoon, and a grown-up to do the popping
- Before you pop your popcorn, put ten kernels in a spoon.
- After it pops, pick out ten pieces. Do they still fit in the spoon?
- Look closely at one piece. Can you find the little bits of brown shell?
What happened? The brown bits are the hull that burst open. The white fluff is the starch that puffed up.
Did you know?
Those few kernels left at the bottom of the bowl? Maybe they had a tiny crack in the shell, or they dried out too much. No trapped steam, no pop. Don't bite them, they are too hard for your teeth!
Every piece of popcorn is a tiny explosion that you can eat.
Your guide in this video
I'm Poppy, a little popcorn kernel. Today we solve a noisy snack mystery!
Poppy is golden yellow with a hard shiny shell. Droppy the water drop hides inside!
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