Question

Identify the prepositional phrase after we finish our reports , we are going to the movies

Answer 1

A prepositional phrase starts with a preposition. Although after can be used as a preposition, in this case it is an adverb, and is followed by a clause, not a phrase. The correct answer is thus to the movies, because the phrase starts with the preposition to. 

Answer 2

It would be after because before,after,in,out,around,up,down are all prepositions!
so its after we finish. Hope it helped!