@clintflint - I'm not sure if that would count as harassment so much as fraud or something else. I think harassment would be if the female students (or, for that matter, the male students) were saying sexually suggestive or threatening things to the teacher to distress him, rather than framing him so he might lose his job.
I guess this is one reason I think sexual harassment is not quite as common for men (although it definitely exists), because it does require a position of power and for most women that power comes from men simply being bigger and stronger than they are. If a woman catcalls a man on the street he doesn't ordinarily have to worry that she's going to follow him into an alley and assault him. So he doesn't feel any fear unless she becomes more aggressive. The same, supposedly harmless, harassment of women does cause fear and that's what shouldn't be allowed because people have the right to live without fear.