The first mistake Scout makes during her first day of school is reading aloud in Miss Caroline's class. Miss Caroline is a young, new teacher in Maycomb County who subscribes to a rigid form of education. She tells Scout to stop reading with her father. Scout tries to defend Atticus by telling her that nobody "taught" her how to read. Scout maintains that she was born knowing how to read because that's what Jem told her.
The second mistake Scout makes during her first day of school is writing a letter to Dill Harris in the middle of a class activity. Scout is bored, and Miss Caroline catches her writing the letter. Miss Caroline reprimands her and tells Scout that they print in first-grade because students don't learn to write until they're in third-grade.
The third mistake Scout makes is attempting to explain Walter Cunningham's family background. When Walter refuses to take the quarter from Miss Caroline for lunch, Scout steps in and tries to explain his situation. She tells her teacher that Walter's family is poor and they refuse to take anything they cannot return. Scout says, "You're shamin' him Miss Caroline," and her teacher gets offended. (Lee 28) Miss Caroline tells Scout she is off to a bad start and gives her a dozen little pats on the palm as a punishment.