What does Scout mean when she says, "Atticus don't ever do anything to Jem and me that he don't do in the yard"?

It's Chapter 5 in To Kill a Mockingbird and Miss Maudie and Scout are having a conversation about the endlessly fascinating Boo Radley and the many legends that have grown up about him over the years. Miss Maudie mentions that when Boo was a young boy he was actually very polite, always speaking nicely to her. In response to a question from Scout, Miss Maudie also expresses the opinion that Boo isn't crazy. But even if he is, we wouldn't know anyway because all kinds of strange things happen behind closed doors, secrets that remain within families without anyone ever finding out about them.
Scout thinks that Miss Maudie is somehow referring to Atticus, although she's actually making a general point. Nevertheless, Scout feels duty-bound as always to defend her father:

"Atticus don’t ever do anything to Jem and me in the house that he don’t do in the yard,” I said, feeling it my duty to defend my parent.

What she means is that Atticus behaves outside the home exactly the same way as he does inside it. His behavior towards other folk in Maycomb is no different from how he acts at home towards his own children. Miss Maudie openly acknowledges this to be true:

Atticus Finch is the same in his house as he is on the public streets.