While Atticus is out of town one Sunday, Calpurnia decides to take Jem and Scout to her own church in the Quarters. She decides that she couldn't trust the children to go to their own church unescorted because of what had happened once before.
Calpurnia evidently remembered a rainy Sunday when we were both fatherless and teacherless. Left to its own devices, the class tied up Eunice Ann Simpson to a chair and placed her in the furnace room. We forgot her...
Scout and Jem get their first real education about Negro life in Maycomb. They are treated warmly by the all-black congregation (aside from Lula) and they see first-hand the poverty of the church and its members. But they also see that the service and sermon is much the same as in their own church, except for things like "linin'," no hymnals and the coffee can collection plate. They also see another side of Cal they have never seen--"a modest double life" in which she spoke quite differently with her black friends than when she is in the Finch house. It gives both of the children a new-found respect for their housekeeper, and as they walk home, Scout asks when she can come visit Cal at her own house in the Quarters.