Although Jem and Scout rarely "dressed up," Calpurnia made sure that they dressed properly on special occasions. She saw to it that Scout was wearing her "pink Sunday dress" at the Missionary Circle tea, and she probably made sure that they were in their Sunday best when they attended their regular church. But Atticus was out of town on this particular Sunday (in Chapter 12), and she didn't trust them to go by themselves (ever since the day Jem and Scout helped tie Eunice Ann Simpson to a chair and left her in the church furnace room). So, when Calpurnia asked Jem and Scout if they wanted to go to her place of worship--the First Purchase A.M.E. Church in the Quarters--they were happy to go someplace new. What they didn't realize was that Calpurnia expected them to look even better than they normally did. She was proud of the Finch children, and since few or no white people attended her church, she wanted them looking their best because how they looked would inevitably reflect upon her as well. Nearly everyone at First Purchase treated the threesome respectfully (except for Lula, who didn't appreciate white faces at her church), and Jem and Scout gained some valuable life experience from their visit.
As was mentioned in the previous post, Calpurnia wanted Jem and Scout to look their best because their appearance would reflect on her. In Chapter 12, Atticus leaves for Montgomery and Calpurnia decides to take the children to her African-American church. The night before the children visit First Purchase African M.E. Church, Cal bathes Scout roughly and makes sure that Jem cleans himself. She also puts extra starch in Scout's dress and rubs her patent leather shoes with a cold biscuit. When Jem mentions that it seems like they are preparing to go to Mardi Gras, Calpurnia says,
"I don't want anybody sayin' I don't look after my children" (Lee 73).
Cal then proceeds to help Jem pick out a tie that will match his outfit. Calpurnia is a prideful woman and wants her community members to know that she is a hard worker. Since Jem's and Scout's appearances reflect on her ability as a housekeeper, Cal makes sure they are dressed properly and look presentable for their first visit to First Purchase African M.E. Church.