Outside, Scout beats Walter up because helping him got her into trouble. Jem stops her, and invites Walter to come eat at their house.
As an older child, Jem is less inclined than Scout to settle things with his fists.
During lunch, Walter talks with Atticus about farm work like a grown up. He says he can't pass first grade because he has to help his father in the fields.
Scout's prejudice that poor people are dumb is shown to be wrong. Poor people are just poor.
As he eats, Walter pours molasses all over his food. Scout is disgusted and says so. Calpurnia pulls her from the table and scolds her, saying Scout should never comment on someone's "ways like you was so high and mighty."
Scout is quick to judge anything different from her way of doing things. Calpurnia, though, insists that Walter, and by extension all people who are different, deserve respect.
Back at school, Miss Caroline screams when she sees a louse in the hair of a filthy boy named Burris Ewell. She tries to send him home to wash his hair, but Burris says he's "done his time for the year." A kid in the class explains that all the Ewell's come to school one day a year to keep the truant officer off their backs, then never come back.
The nasty, brutish, and dirty Burris Ewell serves as the introduction to the Ewell clan, who will play a much bigger role in the second half of Mockingbird.
That night, when Scout says that Miss Caroline wants her to stop reading at home, Atticus counsels that instead of getting angry, Scout should try standing in Miss Caroline's skin to see things from her point of view. He also says he'll keep reading with Scout if she keeps quiet about it.
Scout's first exposure to Atticus's belief in trying to understand and respect other peoples' point of view. Atticus's willingness to keep reading with her, though, shows he doesn't just bow down to authority.