The children's visit to Calpurnia's church is quite an educational experience for Scout and Jem. They discover the depths of poverty that First Purchase must endure in comparison to Maycomb's whites-only churches: There is no electricity, paint nor hymnals, but the church still serves its true purpose. They are welcomed warmly by nearly the entire congregation (aside from Lula), and they see that Reverend Sykes' sermon sends the same message as the ones at the Finches' church. They find that the congregation supports Tom Robinson's family, and Scout finds out for the first time that Tom has been charged with rape--a word that is unknown to her.
Scout also discovers that Calpurnia leads a "modest double life," and her speech is much different when she is surrounded by her friends than when she is with the Finches. Scout gains yet another insight in becoming a lady: Cal explains that "It's not ladylike" to "tell all you know," especially when it "aggravates" others.
"You're not gonna change any of them by talkin' right, they've got to want to learn themselves, and when they don't want to learn there's nothing you can do but keep your mouth shut or talk their language."
Scout takes Cal's advice about tolerance to heart, and she learns to listen and hold her tongue--as a lady should--when she is confronted by others who have not yet learned this trick, particularly Aunt Alexandra and the women of the Missionary Circle.