Everyone is a student and the only thing controlling that is their curiosity. Doodling itself can be a stimulus to curiosity. Here is my latest GeoGebra doodle from this morning. For a copy of the GeoGebra file, click here.
This second one is not a doodle. It is using a specific equation which I had seen somewhere on the web. When I can find it again I will give credit where credit is due. This is just a doctored version of the original. My GeoGebra file is here