In Chapter 9, some of the kids at school, namely Cecil Jacobs, give Scout a hard time because Atticus is defending Tom Robinson. Atticus tells Scout that he must defend Tom on principle and that she should ignore rude comments from the other kids. Cecil gives her a hard time and Scout, for the first time, walks away from a fight.
Atticus, Scout, and Jem spend Christmas with Aunt Alexandra, her husband Jimmy, Uncle Jack (Atticus' brother), and Francis (Aunt Alexandra's grandson). Francis gives similar rude comments to Scout about Atticus defending Tom. Francis doesn't let up and Scout feels so frustrated that she punches him. Uncle Jack breaks up the fight and spanks Scout. Uncle Jack finally listens to Scout's side of the story. At the end of the chapter, Scout overhears Jack and Atticus talking about the difficulties involving the upcoming trial.
In Chapter 10, Scout reveals that she and Jem feel somewhat disadvantaged having such an old father. She recalls the time when Atticus gave her and Jem air-rifles. He would not teach them so Uncle Jack did. Scout also recalls Atticus' statement that it was a sin to kill a mockingbird. After asking Miss Maudie about this, Miss Maudie replies:
“Mockingbirds don’t do one thing but make music for us to enjoy. They don’t eat up people’s gardens, don’t nest in corncribs, they don’t do one thing but sing their hearts out for us. That’s why it’s a sin to kill a mockingbird.”
This establishes the idea that it is a sin to kill or harm something or someone who is innocent. (Tom and Boo Radley will become similar to the mockingbird in this sense.)
Later in the chapter, Tim Johnson (Harry Johson's dog) has become rabid and must be shot. Heck Tate is worried that he will miss and asks Atticus to take the shot. Atticus takes the shot and kills the rabid dog. Scout and Jem are impressed. Scout wants to brag about Atticus at school but Jem tells her not to, concluding that Atticus is a gentleman and gentlemen don't brag about such things.