"Who is teaching your class this year?"

Translation: 今年谁教你们的班？

[NieRenLi]

Chinese grammar usually. follows STPVO.
Subject
Time
Place
Verb
Object

This sentence is still proper, but I could, and usually would, place今年after谁.

[JonChanYS]

With a declarative sentence i would say you are correct, but in this case your advice is absolutely wrong. 誰今年教你們的班 sounds stilted.

[IanMcFarla17]

Since it seems we have here a disagreement between native speakers, it woiuld seem to follow that Duolingo should accept either as permissible.

[ny4MS1qV]

Am I the only one who would say 今年你们班谁教?

[TherMaster11]

I could see someone say that IRL.