Book 1, Question 101 · Video
Why Does Popcorn Pop? A Tiny Pressure Cooker!
Every popcorn kernel is a tiny pressure cooker with water inside. When it is heated, the water turns into steam, and the steam bursts the tough outer shell, called the pericarp, wh
Read the full answer →What Crafty Clover says in this video
Intro
Hi! I'm Crafty Clover! Let's discover something amazing. Why does popcorn pop?
The Big Idea
Every popcorn kernel hides a tiny secret inside: a little bit of water! When it gets hot enough, that water turns into steam, and pop! It bursts into a fluffy snack. Let's see how it works, step by step!
A Kernel Is a Tiny Pressure Cooker
Step one: a kernel is a tiny pressure cooker, with water inside. Its tough outer shell is called the pericarp. Inside are soft starch and tiny droplets of water. The strong shell keeps everything sealed in tight.
Heat Turns Water Into Steam
Step two: heat turns the water into steam. As the kernel heats up, the water inside boils into steam. Steam needs way more room, but the shell won't let it out, so the pressure pushes harder and harder!
Steam Bursts the Shell Into White Foam
Step three: steam bursts the shell into white foam. At about 180 degrees Celsius, the shell can't hold on. Pop! It cracks open. The hot, soft starch puffs out into a fluffy foam, then cools and hardens into the popcorn we eat!
Before and After
Let's look closer! Before: water and starch are trapped inside the hard kernel. After: the steam expands, the shell cracks, and the starch puffs into foam. A popped kernel can grow to about forty times bigger than it was!
Quick Facts
Quick facts! Popcorn pops at about 180 degrees Celsius, or 356 Fahrenheit. A kernel needs just enough water inside. Too dry, and it won't pop! The pressure inside can get about nine times stronger than the air around us. And people have been popping corn for thousands of years!
Think Like a Scientist
Now, think like a scientist! Get an unpopped kernel and a popped one. Compare them side by side. The unpopped kernel is hard, small, and smooth. The popped one is light, big, and fluffy! Draw both, and list the differences. What do you think happened to the water inside?
Outro
Popcorn pops because water inside the kernel turns to steam, and bursts the shell wide open. Pop, pop, hooray! Crafty Clover can be found on Amazon Books, Google Bookstore, and Apple Books. Available for purchase or download! Bye for now!