The Lesson

By taking the children to a fancy toy store, what lesson does Miss Moore intend to teach the children? How does she expect them to act on this lesson? 

What lesson does the narrator actually learn? How is it different from the lesson that she is supposed to learn? 

At the end of the story, the narrator gets a sort of revenge not only on Miss Moore but on her cousin Sugar as well. Why does the narrator trick Sugar in the way that she does?