To Kill a Mockingbird is full of examples of knowledge and ignorance. There are of course the moments when Scout (and Jem and Dill) learns some lesson from Atticus or from Calpurnia and there we see a progression from ignorance to knowledge.
But there are also just as many, or more, moments in the novel when, in seeking knowledge, Scout sees how ignorance is a problem in the adult world. In Chapter 23, Aunt Alexandra is trying to explain to Scout that it is important to be polite to people of a lower economic bracket (or people whose family history is a poor lineage) but not to fraternize with them. Alexandra still ascribes to the traditional social values of the South and this included, at the time the novel is set, rigid social class structures and unequal treatment of African-Americans. Scout questions her on this, asking why can't she be nice to Walter Cunningham, and gets this response: “I didn't say don't be nice to him. You should be friendly and polite to him, you should be gracious to everybody, dear. But you don't have to invite him home” (119). Alexandra then refers to Walter as “trash” and she may as well lump in everyone, from the Ewells to Tom Robinson, who is poor or from “the other side of town.” Scout and Jem begin to see that knowledge for Alexandra is history and tradition. Knowledge for Atticus is literally thinking outside the box of that tradition because that tradition is clearly interwoven with prejudice and ignorance.
This is an interesting moment in the book in terms of knowledge and ignorance because Scout and Jem learn (knowledge) that one of the problems with the adult world is ignorance and prejudice. In other words, ironically, they learn about ignorance. They will also learn about how even adults in powerful, responsible positions can behave ignorantly. Tom Robinson's case is an example. Jem sums this up at the end of the same chapter, 23, when he comes to a realization about Boo Radley. “Scout, I think I'm beginning to understand something. I think I'm beginning to understand why Boo Radley's stayed shut up in the house all this time . . . it's because he wants to stay inside” (121).