In To Kill a Mockingbird, how does Calpurnia affect Scout's life?

Calpurnia is hired by Atticus Finch as a cook, housekeeper, and nanny for Jem and Scout after his wife dies. Scout is two years old when her mother dies, so the closest thing she has to a mother, whom she remembers, is Calpurnia. The novel opens at the time Scout is six and first attending school. Her first day of school is memorable because Calpurnia teaches her a valuable lesson about how to be respectful to others and a good hostess. In chapter 3, when Walter Cunningham comes to lunch, he pours maple syrup on his vegetables and plate. Scout makes him feel ashamed when she rudely asks why he's doing that. Calpurnia takes her into the kitchen and gives her the following lecture:

“Hush your mouth! Don't matter who they are, anybody sets foot in this house's yo' comp'ny, and don't you let me catch you remarkin' on their ways like you was so high and mighty! Yo' folks might be better'n the Cunninghams but it don't count for nothin' the way you're disgracin' 'em--if you can't act fit to eat at the table you can just set here and eat in the kitchen!" (24-25).

The best part is Scout tries to get Cal fired over this and Atticus won't do it. In fact, he reminds Scout that she needs to obey Calpurnia at all times. This event not only teaches Scout to be more respectful towards others, but that Calpurnia is also a valuable person to her father, and will be for her, too. Atticus has so much confidence in Calpurnia, that he refuses to fire her at his sister Alexandra's request as well. He tells Alexandra the following:

"Besides, I don't think the children've suffered one bit from her having brought them up. If anything, she's been harder on them in some ways than a mother would have been . . . she's never let them get away with anything, she's never indulged them the way most colored nurses do. She tried to bring them up according to her lights, and Cal's lights are pretty good--and another thing, the children love her" (137).

Atticus says that Calpurnia is probably the best thing for his children because she's tough on them and they love her. There is absolutely no real reason to keep Calpurnia once Aunt Alexandra moves in with them, so for Atticus to say this and still retain her services is quite a compliment. The best quality that trumps all of the others is the fact that he sees that his children love and respect her. Without a mother, she's the most influential woman in their lives.