In the beginning of the book, Scout tells us that Calpurnia has
"....been with us ever since Jem was born, and I had felt her tyrannical presence as long as I could remember." (pg 6)
However, when they visit Calpurnia's church, they were confronted with discrimination when Lula says that the white chillun have their own church and should not come into a "nigger church". When Lula approaches the children, Calpurnia becomes indignant and tells her that
"It's the same God, ain't it?" (pg 119)
At this point, Scout notices that Calpurnia's language has changed.
"I thought her voice strange: she was talking like the rest of them." (pg 119)
When they entered the church, it was unlike any church they had been in. There were no hymnbooks, no organ, no piano, and no church program. When they sang, one person sang, and then the rest echoed those words. Later when Scout asks why there were no hymnbooks, organ, piano, and why they sang that way, Calpurnia explained that it wouldn't do any good to have those things because..
"They can't read!" (pg 124)
Scout then learns that Calpurnia is one of four people in the whole church who can read and another one is Zeebo, her son. She had taught him to read.
They also realized that Calpurnia led "a modest double life" (pg 125) She had an existence outside of the one that she shared with them, and she spoke black English as well as white English. When they asked her why she didn't speak white English to the black people, Calpurnia tells them,
"Suppose you and Scout talked colored folks' talk at home, it'd be out of place, wouldn't it? Now what if I talked white-folks' talk at church, and with my neighbors? They'd think I was puttin' on airs to beat Moses." (pg 126)
Scout insists that she could teach the black folks how to speak correct English, but Calpurnia states,
"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 and talk their language." (pg 126)
Jem and Scout gained a new respect for Calpurnia during that visit to the church. They understood that she stood up for her principles, she educated herself and her son, and she knew she could speak two languages to make everyone feel comfortable and approachable. Scout realizes the strong separation there is between the two societies and that she can learn something from Calpurnia's life. She asks Calpurnia if she can come to visit her at her home. Calpurnia graciously welcomes her, but Aunt Alexandra quickly puts a stop to that .