I think they could end it out with the events that 10's preview for ep 11 hinted at... but I dunno.

Pretty sure it's going to be 13, but I'm hoping there's room for an S2 in there 'cause it's a really well-done series. Definitely some potential.

Then, going the full-GTO route (here's an angsty student. I'll win that student over by solving their problems. NEXT! Oh look, another angsty student, I'll win them over by solving their problems. NEXT! ....) would get tired pretty fast.