Teresa is in homeroom 62-A, which probably got subdivided along with the dorm rooms, if the name is any indication.
Teresa visits the bathroom with a Seoul girl in her hall and has a superficial conversation in Mandarin on the way to the top floor.
The room itself is crowded, three large tables with chairs and desks crammed in between them with inches between them. The walls seem crowded, too, there are a lot more lamps than necessary to light it. This matches the 'subdivided' theory, possibly?
She's not first, but no one she'd previously noted is here yet. She grabs a pointer resting against and tests a few desks, then takes one that lets her keep her back protected and watch others come in.