THe children are puzzled by Atticus' behaviour in chapter 13. Why did he agree to Aunt Alexandra's visit?

Aunt Alexandra is Atticus's sister and, despite her overt racism, he knows she cares about Scout and Jem. Aunt Alexandra wants to help and he doesn't want to shut her out of his life,

"We felt it was time you children needed--well, it's like this, Scout... Your aunt's doing me a favor as well as you all. I can't stay here all day with you, and the summer's going to be a hot one." Ch 13