Don't talk to the students in front, and don't wake the students behind. Seek the full text of this joke.

When the bell rang, the teacher smiled and said to the whole class: students who are clamoring for school should not panic, and they will not delay class. Please stop chatting with people who eat instant noodles. Tell the students playing poker in the back row to be quiet, and don't affect the sleep of the students in the front row. Students who look at the scenery by the window are called students who play basketball on the playground, so that I can arrange my homework. The students on the road remember to inform the students in the internet cafe about today's homework! Ok, go on, I haven't finished reading my novel.

Or this?

Students in the middle, stop talking! If you are as quiet as the classmate who plays cards at the back, you won't wake the classmate who sleeps in front! The teacher will sing a lullaby!