Bob Ewell spits on Atticus and threatens him. Atticus keeps his cool and doesn't react. Atticus claims he took whatever credibility Bob had left. Jem and Scout are worried that something is going to happen to Atticus.
The Class System
Jem and Scout are asking questions about the justice system. They don't understand how it can be so unfair. Atticus explains to them that race and gender plays a big role in the justice system.
Scout and Aunt Alexandra get into an argument about Walter Cunningham because he is not as high up in the class system as they are. She sees him as trash and says Scout is never aloud to have him over. Jem takes her to his room to comfort her.
There is a class system in Maycomb, there is four different kind of people. There is the ordinary kind like Atticus's family. Then there is the people like the Cunningham's. Next there are people like the Ewells. Finally then the African-Americans.