礼堂(lǐ táng) - assembly hall in Mandarin

礼堂 (lǐtáng) is the assembly hall, the big room where a Chinese school gathers everyone at once: opening ceremonies, prize givings, exam briefings. 礼 (lǐ) means "ceremony, ritual, courtesy" and 堂 (táng) means "hall", so the compound is literally a "ceremony hall".

It is not a classroom and not the canteen. Where 教室 (jiàoshì) holds one class and 食堂 (shítáng) feeds everyone, 礼堂 (lǐtáng) is for occasions that involve the whole school standing or sitting together, usually with a stage at the front.

Watch the measure word: one assembly hall is 一个礼堂 (yí gè lǐtáng), or 一座礼堂 (yí zuò lǐtáng) if you want to stress it as a building.