Scout fights with Francis and Uncle Jack spanks her.
Before visiting her family at Christmas, Scout has had many fights with classmates about her father defending a black man. Atticus tells her she needs to keep her head on straight, and promise to spank her for fighting, but he never has.
Frances and Scout do not get along even before the Robinson case.
He was a year older than I, and I avoided him on principle: he enjoyed everything I disapproved of, and disliked my ingenuous diversions. (ch 9)
Scout and Uncle Jack hit it off on the wrong foot because she is in a swearing phase. He takes her aside and asks her if she likes swear words (which she uses because she hopes Attius will think she picked them up at school and not make her go). Scout tells him she does.
Well I don't," said Uncle Jack, "not unless there's extreme provocation connected with 'em. I'll be here a week, and I don't want to hear any words like that while I'm here. Scout, you'll get in trouble if you go around saying things like that. (ch 9)
Unfortunately, provocation is not far off. Francis does not approve of Atticus defending a black man. He also does not like Scout much. When he insults her because of her father, she feels provoked and attacks him. He tells on her to Uncle Jack, and Uncle Jack spanks her.
Uncle Jack does not understand why Scout is mad at him. He tells her that he warned her. She explains that he is not being fair, because he did not listen to her side of the story. Uncle Jack gets a lesson in fairness, and in children. He realizes things are not always what they seem.