But Why: A Podcast For Curious Kids

How do popcorn kernels pop? How do salmon know where to return to spawn? How do rabbits change colors? Why does television fry your brain? How do zippers zip stuff? Who was the fastest runner in the world? In this episode, we'll tackle all of these questions! Download our learning guides: PDF | Google Slide | Transcript Inside the husk is a tiny little droplet of water surrounded by something called the endosperm. The endosperm is what you're actually eating when you eat popcorn. When you heat up popcorn, the tiny droplet of water gets hot and turns into steam. That steam pushes through the endosperm and turns it kind of soft and that endosperm builds up pressure and explodes through the husk. When it explodes, that soft gelatinous endosperm hits cooler air and it hardens up in whatever shape it has exploded into. So that's why popcorn has all those funny shapes and feels kind of like foam. Salmon are born in freshwater, but then spend their lives in saltwater. They return to the freshwater to spawn (lay