In To Kill a Mockingbird, why does Calpurnia speak differently at her church than she does with the children in their home?What is Lee illustrating...

In To Kill a Mockingbird, Calpurnia is one of the fortunate African Americans in Maycomb County in that she is able to read.  She also works for Atticus Finch, a lawyer and single father who treats Calpurnia as if she was one of the family.  As such, she speaks much like the members of the Finch family when she is there.  However, while she is with the members of her own community, Calpurnia uses the dialect of her people so that she will be more readily accepted.  She does not want her people, especially members of her church, to think that she is under the impression that she is better than them because of the way they speak.  It is a matter of assimilation on Calpurnia's part so that she will be accepted in both communities.