You can call the kid who is always really nice to the teacher in hopes of getting a good grade a brown-noser or, if you want to sound clever, a toady.

Pronunciation: /'todi/
English description: a person who tries to please someone in order to gain a personal advantage
Synonyms: ass-kisser
Chinese Translation: 谄媚(xian4 mei4)
Spanish Translation: pelotillero
ORIGIN: The word toady has a gross, yet engaging history. Back when medicine was more trickery than science, traveling medicine men would come to a town. Their assistant would eat a toad (you read that right) that was assumed poisonous so that the medicine man could "heal" him. Who would want that job, right? So toad-eater, later shortened to toady, came to mean a person who would do anything to please his boss.

EXAMPLE SENTENCE:

She disliked attending parties — “the toady circuit,” she termed it — and preferred to gather details over the phone.
It wasn't just blind loyalty, though, toadying up to the manager - more a conviction that given time he would come good.

*New word description, story and part of "EXAMPLE SENTENCE" are cited in Vocabulary