Editor lhc is correct, though I would also add that author Harper Lee based the fictitious town of Maycomb on her actual hometown, Monroeville, Alabama. I have visited Monroeville and have found it to be a small town that values its literary heritage and maintains as much as possible the small-town people and down-South values of which Lee writes in her novel.
Unfortunately, some of the "down-South values" prevalent during 1930s Alabama involved some incredibly racist attitudes and overall prejudiced actions. This is where Scout's teacher's disparaging comments about Tom Robinson come into play. Scout recalls:
Well, coming out of the courthouse that night Miss Gates [...] [said] it's time somebody taught 'em a lesson, they were gettin' way above themselves, an' the next thing they think they can do is marry us (Lee 331).
This quote speaks to the racism and hypocrisy of the era -- and insinuates that the "education" Scout is getting seems to perpetuate ignorance rather than the pursuit of knowledge.
Earlier in the novel, Miss Caroline, Scout's first grade teacher, even tells Scout, in so many words, that being completely literate in the first grade is not normal, commanding,
"Now you tell your father not to teach you any more. It's best to begin reading with a fresh mind. You tell him I'll take over from here and try to undo the damage."
She then proceeds to demean Atticus by reminding Scout that he is not a teacher, but she is (Lee 23). This instance of perpetuating ignorance rather than knowledge seems, in this case, to stem from Miss Caroline's personal feelings of inadequacy and her need to feel superior. Location and societal expectations also play into this discouragement of learning (many of Scout's peers did not take education seriously, which she mentions in her comment that many of them were repeating first grade -- page 22)
Throughout the novel, Scout's teachers are just as much products of their environment as their students. Sometimes caving in to societal expectations (and the lack thereof), they can tend to follow popular opinion or the status quo.
You might begin by looking at some clear weaknesses in the school Scout and Jem attend. On Scout's first day, she is told by her teacher that she cannot read newspapers with her father anymore, because he doesn't know how to teach reading. This teacher either disregards or doesn't recognize that Scout already knows how to read. Another nuance that might be interesting to explore would be the prejudiced comments by Scout's teacher as the trial of Tom Robinson gets underway; although she had delivered an enthusiastic commentary to the class on the contributions of Jews to civilization, Scout later overhears her discussing the need to keep blacks like Tom Robinson in their proper place in society.