Why does Aunt Alexandra come to stay with Atticus, Jem and Scout for the summer?

Aunt Alexandra has decided (and convinced Atticus) it would be best for the family if she stays with them for "a while," which worries Scout even though she knows there's nothing to be done. She wants to influence Scout and make her a lady, all while helping with thechildren during the trial. Alexandra also hopes to teach the children about their heritage and instill a sense of family pride.