Excision theorem

Alright, let me try to explain the excision theorem to you like you're 5 years old!

Imagine you have a bunch of stickers and you want to put them on a big sheet of paper. Now imagine the sheet of paper is a shape, like a circle or a square or a triangle. Sometimes, you only want to put the stickers on a part of the shape, like just the top half of the circle.

The excision theorem is kind of like that. When we study shapes in math, we sometimes want to focus on just part of the shape. And the excision theorem tells us that we can do that without changing the math rules we use to understand the whole shape.

So if we have a shape and we cut out a part of it, we can still study the remaining part without worrying that our math rules won't work anymore. Kind of like how you can still put stickers on the bottom half of the circle even if you cut out the top half.

I hope that helps you understand the excision theorem a little better!