If you've watched many YouTube videos on math and science or taken online courses in the same, you've probably seen the [Lightboard](https://www.lightboard.info/), a transparent chalkboard where the instructor can stand on the opposite side and Lightboard was invented by Michael Peshkin, engineering professor at Northwestern University. Lightboard is an example of [[open source hardware]], which I didn't even know existed until encountering this clever piece of technology.