In Harper Lee's To Kill a Mockingbird, we find Jean Louise "Scout" Finch in the third grade. Her day at school in Miss Gates' class has raised some questions in her mind. A discussion of current events raised the subject of Adolf Hitler's persecution of the Jews. Scout's teacher, Miss Gates, was very angry about Hitler's actions.
After school, Scout asks her older brother Jem about whether Miss Gates was a nice person. Jem recalled that she was. When Scout wonders whether it is right to persecute anyone, Jem agrees that it is not. This leads Scout to recall a comment Miss Gates made when they were leaving the courthouse about the need for someone to teach persons of color a lesson, so that they would not think that they were good enough to "marry us."
When Jem hears this remark, he becomes very angry and tells Scout that "I never wanta hear about that courthouse again".
Atticus seems to attribute Jem's anger to an inability to process his feelings about the trial at that particular point in time. Atticus suggests that at some point later in life Jem would come to terms with what happened in the trial of Tom Robinson, whom Jem did not expect would be found guilty.