"The teacher puts the student into the room."
Translation:Die Lehrerin stellt den Schüler in das Zimmer.
It is correct. "Der Student" is declined to "den Studenten" in accusative, and to "dem Studenten" in dative. As if it was plural.
Sadly, Duolingo has done a terrible job of warning (I won't say teaching) users that nouns are also declined in German. That entire issue goes unmentioned. When it comes to learning grammar, and grammar one must learn, Duolingo is not the right place to go.
"den Studenten" is quite correct, but "stellt" is out of place here. That is what you can do to an inanimate object like a flowerpot or an umbrella. As long as the student is a living person (not a statue or a mummy), you cannot really use "stellt"
There is no German word as broadband as "put".
According to the situation you can use:
"steckt" (rather unfriendly act)
"setzt" (a chair or stool or something is involved)
"bringt" (a bit more about leading him there than putting him into the room)
"sperrt" (the teacher puts him there and locks the door")
That's right. Stellen is a verb of action/movement, so you get to use the accusative.
It may be of help if you think about it in terms of you being seated on a chair. Any verb that requires you to get up of that chair to perform the action uses the accusative. If you can complete the action without needing to move away for your chair, you get to use the dative,