ELI5: Explain Like I'm 5

Figure-eight knot (mathematics)

Hey kiddo, have you ever heard of a knot? It's something you do with a piece of rope to tie it together so it doesn't come undone. Well, there's a special kind of knot called a figure-eight knot that is used a lot in math and science.

Picture drawing a number 8 on the ground with a stick, but when you get to the part where the top loop touches the bottom loop, you bring the stick back up and over the top loop again instead of connecting it. That's a figure-eight shape!

Now if we take a long piece of rope and tie it into a figure-eight knot, we can use this knot in lots of different ways. It's really strong and won't slip undone easily, which makes it useful for things like rock climbing or tying a boat to a dock.

In math, we use the figure-eight knot to describe shapes with certain properties. When we look at a figure-eight knot, we can see that it has a lot of twists and loops that make it really interesting to study. We can even use math to figure out how many different ways there are to tie a figure-eight knot!

So that's a figure-eight knot in a nutshell, kiddo. It's a special kind of knot that's really strong and interesting to look at, and we can use it in lots of different ways – both in the real world and in math!