In Alabama in the Great Depression, racism was rampant. In chapter 12 we learn a lot of historical information about Maycomb.
Atticus is called into an emergency session of the state legislature to deal with some issues.
[There] were sit-down strikes in Birmingham; bread lines in the cities grew longer, people in the country grew poorer. (ch 12)
Scout notes that these events are remote from her world, but they really are not. Racial unrest and poverty are affecting Maycomb as well. This hits home when Calpurnia, the black housekeeper, takes the children to her church, First Purchase, and they are not well-received by some because they are white and they are outsiders.
There seems to be a conflict with Lula, a woman at the church. Cal said that the kids were her company.
"Yeah, an' I reckon you's comp'ny at the Finch house durin' the week." (ch 12)
This comment highlights the race and class relations in Maycomb. Calpurnia’s white children are her employers, not her friends.
Scout notices that Calpurnia speaks differently at the church. She does not sound educated. Calpurnia has to talk differently there or she would seem proud when talking to the other less-educated people.
The children also notice that few people are reading from hymn books, and it is because most of them cannot read. They don’t have access to the educational opportunities even some of the poor white kids have. The children have never asked Cal when her birthday is, and it turns out she doesn’t know. The only reason Calpurnia can read is that their grandfather saw to it that she had some education.
There were massive issues going on about the segregation of blacks, and the civil rights movement was just about to start.