What examples from To Kill a Mockingbird provide evidence that Atticus Finch taught his children that prejudice was wrong?

Once Cecil Jacobs antagonizes Scout in chapter 9 about her father defending a black man, the prejudiced comments seem to build and increase towards the Finches as the trial nears. Atticus doesn't tell Scout that these are prejudiced comments, but he does advise her to be aware of them and to fight against them by not allowing them to hurt her.

“You might hear some ugly talk about it at school, but do one thing for me if you will: you just hold your head high and keep those fists down. No matter what anybody says to you, don’t you let ‘em get  your goat. Try fighting with your head for a change . . . it’s a good one” (76).

At this point, Atticus knows that these comments may hurt Scout's feelings. That's enough of a lesson in and of itself. By Scout experiencing what it feels like to be the brunt of prejudiced comments, she may learn on her own that being prejudiced is wrong. However, Atticus is still concerned by Christmas when he speaks about the upcoming trial with his brother Jack, as follows:

“You know what's going to happen as well as I do, Jack, and I hope and pray I can get Jem and Scout through it without bitterness, and most of all, without catching Maycomb's usual disease. Why reasonable people go stark raving mad when anything involving a Negro comes up, is something I don’t pretend to understand" (88).

With this passage, Atticus refers to "Maycomb's usual disease" which is prejudice and racism. He hopes that his children won't turn into the same type of people he's fighting against by defending Tom honestly and honorably. When adults like Mrs. Dubose start throwing obscenities at his children, he is given another opportunity to teach his daughter how to fight it, as follows:

“Scout. . . ni****-lover is just one of those terms that don't mean anything--like snot-nose. . . ignorant, trashy people use it when they think somebody's favoring Negroes over and above themselves. It's slipped into usage with some people like ourselves, when they want a common, ugly term to label somebody. . . baby, it's never an insult to be called what somebody thinks is a bad name. It just shows you how poor that person is, it doesn't hurt you" (108).

Atticus's main focus is to teach his children to ignore people who are prejudiced and not allow these people to hurt their feelings. In addition, he calls these people "ignorant" and "trashy," thereby letting Scout know that they are not behaving appropriately towards others. He does it in such a kind way, though, that Scout doesn't know that she's learning about the word "prejudice." Even though Atticus preaches passivity to people's prejudiced comments, that does not mean that he condones them.