In Chapter 2, how does Harper Lee use the school setting to give the reader important exposition about Southern culture?

Lee cleverly uses the character of Miss Caroline as an outsider's perspective to show readers a full picture of Maycomb, and through Maycomb, Southern culture.  Seeing Miss Caroline interact with the kids is like looking through a television or at a picture.  Her misunderstandings help Scout as narrator to better explain her world.

For example, Miss Caroline tries hard to discipline the Ewell boy and to bring him in as a part of the class.  This allows Scout to explain that the Ewell's don't go to school and that the school accepts this.  She also explains the nature of the Ewell family.  Readers understand that part of the Southern culture includes both poverty and ignorance, people trapped into past behaviors who are unwilling to expand their horizons and change their ways.  The situation with Walter Cunningham shows also demonstrates the past.  Walter is a victim of poverty.  Walter's father uses the barter system, which is accepted by the town members, in order to pay his bills.  This situation also demonstrates Southern pride.  Walter is proud and honest.  He can not pay back the quarter Miss Caroline tries to lend him and so refuses to accept it.

Overall, Miss Caroline is pitied by the children because she doesn't understand the culture of Maycomb - which proves how important culture and tradition are in Southern communities.