https://knowyourmeme.com/memes/loss

There was a webcomic series called Ctrl+Alt+Del and Loss is one of those comics that depicted a man rushing in the hospital and finding his wife had a miscarriage. It was a drastic shift in tone from the normally video game related lighthearted series. The original comic is a 4 panel in a grid displaying:

The man coming in the hospital (single upright figure)
The man speaking with the receptionist (2 single upright figures)
The man speaking with the doctor (2 single upright figures)
The man looking over his wife in bed (1 upright figure and 1 horizontal figure)

It's since been parodied in many ways, while keeping the basic structure the same, mostly in minimalist depictions. If you look at the teacher's graphic, it has that same structure. Those that are familiar with the original comic and it's many parodies can usually notice it right away.

I think it's a perfect example of the teacher's lesson showcasing a "glyph" that would be completely unrecognizable to anyone who isn't familiar.