Given Scout's first-grade experience, it would be safe to say that Harper Lee thought education was something that happened despite, not because of, the public school system. Scout enters public school having learned to read on her own, almost by osmosis, from sitting on Atticus's lap and following along while he reads. She has learned to write from Calpurnia. Her teacher, however, says it's wrong for her to read and write at home. Instead, the teacher, Miss Caroline, wants the students to learn words from little cards she holds up and to read the stories she wants them to read.
Scout is so outraged by the whole school situation that she insists to Atticus that she won't go back. She doesn't want to give up her self-education. Atticus strikes a deal with her, saying,
“If you’ll concede the necessity of going to school, we’ll go on reading every night just as we always have."
He also tells her to try to see things from Miss Caroline's point of view, and not to tell Miss Caroline about the deal she has made to read at home. What the reader learns from this episode is that school is a place you tolerate and work around, but that one's real education occurs outside its walls.