教室(jiào shì) - classroom in Mandarin

教室 (jiàoshì) is the classroom, the room a class actually sits in for lessons. 教 (jiào) means "to teach" and 室 (shì) means "room", so the compound reads plainly as "teaching room".

It pairs constantly with words for the school day: 走进教室 (zǒu jìn jiàoshì), "walk into the classroom", and 教室里 (jiàoshì lǐ), "inside the classroom", are both everyday phrases. Do not confuse it with 教师 (jiàoshī), "teacher", a near-homophone that trips up a lot of learners because only the tone on the second syllable differs.

The measure word is 间 (jiān), the one used for rooms: one classroom is 一间教室 (yì jiān jiàoshì).