Well, as others said nothing stops her being a second teacher or a different staff like the school nurse. Tell me you wouldn't like the idea of the school nurse.
But you are thinking of this by the lens of Evolution... which is fair, considering the name and that at the start, the first two girls, Rogue and Kitty followed the designs from there.
But Laura is older, being closer in age to the first two here while there she was visibly much younger, closer to her comics age. Emma did not even appear, as far as I remember, nd if it did it was more of a cameo like Jubilee, not a teacher. And Jean looks very different from the one there (which is in my opinion her hotter design save for her phoenix forms, shame), to the point people have trouble recognizing her (not even counting the change in personality that is supposed to just be hidden from the public), the only one I can recall to look like that is her Ultimate universe form.
So Ororo doesn't need to be the same age as in there, so no need to be a teacher.
In the older cartoon, in the first movies, and I think also the first comics she was in, she was the same age as the main cast of Cyclops, Jean, Rogue etc. Meaning there shouldn't be a problem just aging her down a bit.
Speaking of alternate universes, people seem to like the idea of GwenPool... but what about Spider-Gwen?
