訓 むろ ・ 音 シツ
漢越音: thất
Roof radical 宀 plus 至 (arrive): the place you reach inside a house. Han Viet that, as in noi that (interior); 教室 is a classroom.
Stroke data: KanjiVG (CC BY-SA 3.0) — kanjivg.tagaini.net
教室に学生が三十人います。 (きょうしつにがくせいがさんじゅうにんいます)
There are thirty students in the classroom.