What does it mean to have integrity, and where in the novel To Kill a Mockingbird does it show integrity? (quotes and page, please)
Having integrity means being genuine, honest, and morally upright; that is, living according to what one believes is morally right and true. One example of the integrity of Atticus is in Chapter 9.
In this chapter Atticus speaks privately with his brother Jack about the upcoming trial of Tom Robinson, who is charged with rape. Since Atticus has been assigned to defend Tom, Jack asks his brother, "...how bad is this going to be?" Atticus tells him it is a terrible situation because the case is simply based upon the accuser's word against Tom's, and the jury is not likely to take Tom Robinson's word against that of the Ewell's, even though they are trashy.
Then, Jack asks Atticus if he cannot avoid taking this case. Atticus tells Jack that if he does that, he cannot face his children.
"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." [p.93 in paperback edition]
Here the integrity of Atticus is exemplified by his refusal to take an easy way out. He feels he must take the case because of the principles that he has taught his children, principles such as the right that every person deserves justice, and every person's life is important. He must stand by these principles, and be morally upright.