Hypotrochoid

Imagine you have a toy that has a big wheel and a smaller wheel inside of it. When the big wheel spins, it makes the smaller wheel spin too. Now, imagine you have a pen tied to the smaller wheel so that when it spins, the pen moves in a special way to make a pretty picture.

A hypotrochoid is a special kind of picture that is made by the pen moving in a specific pattern on a piece of paper. This pattern is made by spinning the big wheel and the smaller wheel inside it at the same time. The pen will move in a wavy line, kind of like a roller coaster track.

The cool thing about hypotrochoid pictures is that you can make them look different by changing the sizes of the wheels and the way they spin. You can make really complex and intricate pictures, or you can make simple ones. It's all about playing around with the toy and seeing what different patterns you can make!