If you teach any kind of class, in my case intro-electrical engineering, amateur radio, and goat health management; then diagrams and flow charts can be a very useful teaching tool. A great way to make quick and easy flow charts and diagrams is using the Dia application.
Open your Software Manager in Linux and do a search for Dia.
The software is so easy to use, that you’ll be up and creating diagrams almost instantly!
My quick example above, of course can be prettied up with different colors, backgrounds etc.
Once you create your diagram masterpiece, you can export it to many common image formats.