Answer :
You're right, the heading is a short catch to start the story, but the title usually goes above it. The title's primary role is to make people pay attention to your text before they start reading it. Maybe your teacher meant that there is a short sneak peek to your story, but it isn't included in the text itself, and then the title goes with the proper text below. That's the only explanation that comes to my mind - otherwise your teacher's quest doesn't make a sense to me at all :)
