Pseudosphere

Imagine you are playing with a really squishy ball that you can stretch and squish however you want. If you take the ball and make a little dent in it with your finger, you'll see that the surface around that dent is kind of like a saddle. This shape is called a "saddle shape."

Now imagine that instead of a ball, you have a flat piece of paper. If you try to make a saddle shape with that paper, you'll see that it's really hard to do without ripping the paper. But there's a special kind of shape called a "pseudosphere" that looks like a saddle shape but can be made out of a flat piece of paper without ripping it.

Scientists and mathematicians really like studying pseudospheres because they are interesting shapes that help them understand how things like gravity work in space. But for now, just remember that a pseudosphere is a shape that looks like a saddle but can be made without tearing paper.