What day (of the week) is tomorrow? = ʻO ka pōʻahia ka lā ʻapōpō?
Tomorrow is Thursday. = ʻO ka Pōʻahā ka lā ʻapōpō.
I agree that word "pule" is not in the original sentence but I wish the graders would be consistent because in other sentences in which "pule" does NOT appear, they translate it as "The concert is on what day of the week?"