Scout is seeing that Miss Caroline is arguing with Walter because he didn't bring his lunch and he didn't forget it, he didný bring it.
Scout is hearing the conversation that Miss Caroline with Walter and Scout wants to defend him. She tells the teacher that he is a Cunnigham and that Cunninghams don't bring lunch and she insisted he accept her quarter but he refused.
After the discussion, Scout and scout found each other and started talking. She later invites him to come and eat. So then she showed him to Jem. Later they pass by Boo Radley house and explaining that to him.