In "To Kill a Mockingbird", how do the children feel at Calpurnia’s church? What do they learn from this visit?

One of the most important things that the children learn from their visit to Calpurnia's church is that, despite differences in worship methodology, church was essentially the same as going to "white church."

Through their encounter with an unfriendly woman at the outset of the service, they also learn that difference is guarded against in other social circles, as well.

However, due to Calpurnia's calming influence and her defense of the children, they also figure out the true value of Calpurnia as a friend as well as a household member.