In "To Kill a Mockingbird" what is chapter 3 about?
In chapter 3, we find Scout bullying Walter Cunningham on the playground during lunchtime; she blames him for a lot of her difficulties at school that morning. Jem intervenes and all three go back to the Finch household to eat lunch. Walter is so starved that he pours syrup all over his food, and Scout stares rudely, and is commenting, "But he's gone and drowned his dinner in syrup," Calpurnia intervenes and gives her a stern lecture on the proper way to treat company.
They finish lunch and go back to school where the teacher, Miss Caroline, becomes freaked out by a louse on Burris Ewell's head. Another student, called Little Chuck, intervenes, and calms Miss Caroline down as Burris kills the louse. Miss Caroline tries to get Burris to leave; he argues with her about it, and it escalates. Little Chuck again intervenes, and tells Burris to leave. He finally does, but not before shouting insults at the teacher, making her cry. She finishes out the day by reading the kids a story.
That evening at home Scout tries to convince her dad that she shouldn't have to go to school, just like Burris, but Atticus disagrees, saying, "You must obey the law." I provided a link to another chapter summary below, and you can find other resources for the book there also.