The easiest bet is to actually draw on a piece of glass and there are actually boards made for just that purpose for the classroom. It is probable one of those is being used here and the video reversed to make it readable from the other side. This seems likely as the video shows the guy left handed and the buttons are on the wrong side of his shirt.

The same look can kind of be achieved using write-on effects and/or animation, but you would still need some prop for the speaker to interact with so that they position their hand in roughly the right area and it still wouldn't like up exactly.

Doing this kind of shot practically is the best way to achieve it.