What is concave?

A concave shape is like a cave that’s been carved into something you see every day, like a bowl or a spoon.

Imagine holding a spoon in your hand. If you look at the inside of it, it curves inward, just like a real cave. That curving-in part is what makes it concave. It's the opposite of something that bulges out, like the outside of a bowl or the top of a mountain.

If you have a bowl, the inside of it is concave, it’s all curved inwards so you can hold soup or cereal. Now imagine flipping that bowl upside down. The part that was inside is now on top, and it still curves inwards, that's still concave, even though it's flipped.

Think of a dent in a metal plate, like when you hit your bike with a rock. That dent curves inward, making it look like a small cave. That’s concave too!

So remember: concave is like a cave inside something, it curves inward, just like the inside of a spoon or bowl.