As in the incident with Uncle Jack, Scout teaches an adult something in Chapter 13 of To Kill a Mockingbird. What do you think Atticus learns?
In Chapter Thirteen, Aunt Alexandra convinces her brother to teach Jem and Scout about their family's history and possibly use his influence to encourage them to behave like proper children. When Atticus enters the children's room before bed, he attempts to explain to them that they come from a prestigious, respectable family and should behave like a little lady and gentleman. However, Scout gets bored and begins to fidget as her father attempts to have a serious conversation with them. Scout then bursts into tears and attempts to run whenever Atticus yells at her to put the comb down. Scout ends up running into her father's stomach, and he realizes that he has been acting differently towards his children. Atticus learns the importance of remaining true to himself and not being influenced by those around him. Atticus has clearly taken up the task of teaching his children about their hereditary after listening to Alexandra. Scout's reaction also teaches her father that there are far more important things in life than impressing others.
Atticus learns that he must follow his own instincts when it comes to dealing with his sister, and he recognizes that forcing himself to defend Alexandra's belief that the children must behave as a Finch is not a good fit. As Atticus has discovered before--at Miss Maudie's house fire and in his discussion about Mrs. Dubose--"It's not time to worry" yet, and he sees that his children are both unprepared and unwilling to begin "to try to live up to your name." Atticus does not really believe Alexandra's views on the glorious past of the Finch family, and he is certainly not comfortable defending them. After he brings Scout to tears trying to force the importance of "gentle breeding" on her, it takes his daughter's own motherly concern about Atticus's "growling" stomach and how "You better take some soda" for him to finally abandon Alexandra's demands. "Forget it," he tells Scout, and
... I knew he had come back to us.