"But ain't nobody gonna beat me at nuthin."

With these words, Sylvia stands in defiance of everything that has happened within the story. Depending on how you look at it, this notion has various meanings. First, it has a physical aspect—that of Sugar racing away from her. Throughout the story, Sylvia 'competes' with the other children in different ways: her plan to jump out of the cab and run to "the first bar-b-que" they can find gets thwarted by the other kids's lack of willingness to join her, they all share stories of their successes and failures of sailing their toy boats, and she admits that she once failed to follow through on a dare to enter a church and begin tap-dancing.

Second, there's the concept of the children's knowledge gained through their shared experience. Just prior to this sentence, Sugar answered Miss Moore's question about the meaning behind their field trip, delighting the impromptu teacher while simultaneously angering Sylvia; she, on the other hand, focuses on the money she kept after paying the taxi driver. This contrast between the two children suggests that the latter has not learned Miss Moore's lesson, but given her defiant nature, it could also be that she does not want to give Miss Moore the satisfaction of having taught her a lesson.

Lastly, though she does not appear to have gained the level of understanding of socioeconomic inequality that Sugar has, Sylvia's statement that "nobody gonna beat" her is a clear indication that she has begun to understand how it affects her. This is the strongest notion left to the reader. Though she did not answer Miss Moore's question, one gets the sense that Sylvia plans on doing everything she can to make sure she does not get "beat" by an unjust and unequal society.

The last line of "The Lesson" is "But ain't nobody gonna beat me at nuthin." This has a few closely related meanings. First, of course, the local and literal meaning: the narrator (Sylvia) isn't going to let Sugar beat her at running, no matter what. Second, and more importantly, Sylvia has learned a more general lesson through the events of the story. She isn't going to let anyone beat her, which also means, she's not going to accept being poor, or being considered second class in any way. Sylvia has reached a point where she's committing to shaping her own destiny. That's the biggest lesson of the story.