Example sentences
wǒ我men们zài在jiào教shì室shàng上kè课。
We have class in the classroom.
jiào教shì室lǐ里yǒu有èr二shí十gè个xué学sheng生。
There are 20 students in the classroom.
About this word
教 is "teach" and 室 is "room", so 教室 is a teaching room. 室 names a room by its function and almost never stands alone, which is why you meet it in 办公室 (office), 卧室 (bedroom), 会议室 (meeting room) and 教室. Watch the reading: 教 is jiāo when it is the verb "to teach", as in 我教你, and jiào inside nouns and compounds like 教室, 教师 and 教育. For the occasion rather than the room, Chinese switches to 课堂, as in 课堂上, "in class".
The story behind the character
教
教 is a hand holding a stick over a child. The left side is 孝, which already contains 子 (a child), and the right side is 攵, a hand with a rod. Xu Shen wrote 教, 上所施下所效也: what is laid down from above, what is imitated from below. The rod is right there in the character, and the ancients drew it without apology.
室
室 is 宀 (a roof) over 至, which gives the sound. But 至 also means "to arrive," so you can read the whole thing as the place you arrive at under a roof. Xu Shen put it short: 室，實也. A room is the thing that gets filled. Look around any room in your house and it is doing exactly that.