Author Harper Lee presents a harsh view of modern education in To Kill a Mockingbird. Scout's teachers are poor examples of educators: Scout recognizes that her third grade teacher, Miss Gates, is a hypocrite; and her first grade teacher, Miss Caroline, is critical of Scout's advanced reading skills. Without knowing anything about Atticus Finch, she declares to Scout that
"Your father does not know how to teach."
Perhaps Miss Caroline is right: Atticus never attended public school, being educated at home; but no one in Maycomb is wiser or more intelligent, and he does his best to pass on his wisdom and experience to his children. He gives them more freedom than most kids their age, and through their exploits--primarily by their constant pursuit of Boo Radley and their unobserved attendance at the Tom Robinson trial--the children learn far more about life than they do in the classroom.
Jem's and Scout's neighbors prove to be far better teachers than Miss Caroline and Miss Gates. Miss Maudie explains to the children about Atticus's motives and his importance to the town; Calpurnia teaches them about manners and proper behavior; Miss Stephanie teaches them that gossip is rarely true; Boo shows through his unseen actions that kindness comes in all forms of men; and even the "evil" Dolphus Raymond helps Dill to understand why he is crying. School will get better for Scout, and the football team becomes a lure for Jem, but the children will probably benefit more from their time spent outside the classroom than within.
For example, when Scout doesn't understand why her teacher is angry with her when she tries to explain why some students won't have a lunch or accept a "loan", she asks her father. He gently tells her about understanding others by putting themselves in the others' shoes...
As well, Scout's teacher "disapproves" of Scout being able to read, having been taught at home and not by the new "official" method. Scout's father makes a deal with her that allows her to still read, but also allows her teacher to save face.
Scout's father is teaching her important life lessons - how to help others from humiliation, how to hold her temper, etc. These are not things she would learn in school.