Answer:
The tone of To Kill a Mockingbird changes over the course of the novel from chatty and innocent to dark and knowing as Scout loses a degree of her innocence. At the beginning of the novel, as Scout recounts a series of anecdotes describing growing up in a small Southern town, the tone is light and nostalgic.
Chapter 12 of Harper Lee's To Kill a Mockingbird takes place mainly in the church that the Finches' housekeeper Calpurnia attends. Being in this African-American church sparks Scout and Jem's curiosity about Calpurnia's life--in an environment very different from the one they know.