教室

How it works

This is a casual see-you-later fragment, not a full sentence — the verb is left unsaid because both people know it ("let's meet"). で (at) marks 教室きょうしつ (classroom) as the place where the action happens, so it reads "in the classroom." The friendly ね (right?) at the end seeks a soft nod of agreement, like "okay?" — turning a plan into a shared one.