YouTube is singularly how high schoolers and college students pass most of their classes, because teachers are not competent instructors. Again, most of these things have gone online, with pre recorded videos being the focus. YouTube content creators simply do a better job at it because math, history, philosophy, etc teachers are poor presenters of information.

Compsci is a popular one where the concepts are far easier understood by a YouTube video than a smart board.

The ideas of what teachers do and what they actually do are entirely different. Teachers overwhelmingly are there to hand out assignments bought from a company. If you don't understand it, teachers don't care, it's keep up or drop out.