Medium to large lecture classes can probably work pretty well. As can mostly small seminars I would think. Other things are tough or impossible.

For example, I had an undergraduate thesis in my major, which required being physically in a lab and having access to a machine shop. In any case, there are lab/project classes throughout a lot of STEM majors that students aren't going to be able to reasonably finish this semester. I don't know how this is being typically handled with everyone having to drop things ~ 1 month into the semester.