How does Atticus show integrity three times in the novel To Kill a Mockingbird?
Integrity means that a person does the morally and ethically right thing for the right reasons. It also means that the way a person accomplishes a task is done honestly. The three ways that Atticus shows integrity are by treating Mr. Cunningham fairly with regards to legal fees; by honestly defending Tom Robinson in court; and by not wanting to cover up his son's possible involvement in Bob Ewell's death.
First, when Jem asks his father if they are poor in chapter two, Atticus humbly says that they are. When Scout asks if they are as poor as the Cunninghams, Atticus says they are not that poor because the crash hurt farmers more than it did professionals. As a result of the Great Depression, and the fact that so many people had resources more than money, Atticus accepts payment for legal services in kind; that is to say, Mr. Cunningham is allowed to pay with what he has on hand rather than with money. Scout remembers finding hickory nuts, stovewood, and similax as forms of payment in the backyard from Mr. Cunningham. Atticus could have taken advantage of his client, but because he has integrity, he tells Mr. Cunningham to stop paying him in a timely manner.
Next, Judge Taylor appoints Atticus to defend Tom Robinson because he knows Atticus will do an honorable job. Most of Maycomb is racist and applies social, political, and verbal pressure on Atticus for intending to do his best for his client. Most people in Maycomb would prefer that Atticus does a poor job of defending Tom in order to show loyalty to his race. Atticus doesn't believe in that way of thinking. In fact, Atticus tells his brother Jack the following about his intentions:
"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).
Atticus refuses to cower in the face of opposition. He doesn't have "Maycomb's usual disease" of prejudice, so he stands up for what he believes by defending Tom Robinson with an honest and honorable effort.
Finally, Atticus shows integrity on the night that Bob Ewell attacks his children and dies. At first, Atticus thinks that Jem killed Bob Ewell in the scuffle. He is willing to bring his son before the judge and plead self-defense. This shows that Atticus is not the kind of man who hides anything, even if he finds himself getting the short end of the stick. Fortunately for him, Heck Tate figures out what happens that night and it wasn't Jem who killed Ewell; it was Boo Radley. Atticus isn't such a straight arrow that he can't bend the rules a little to do the right thing, though. He supports the sheriff's cover-up to say that Ewell fell on his own knife in an effort to secure Boo Radley's privacy.
Atticus displays integrity throughout the story. Integrity is one of the biggest themes of the story - the idea of doing right just because it is right, regardless of whether it is popular.
The most obvious instance of Atticus choosing to do right even though it is unpopular is his insistence on a fair trial for Tom Robinson. This goes against what much of the community wants and even places him in a position where he might be injured or killed. It also jeopardizes his children, and while he takes measures to protect them, he does not sacrifice integrity to do so.
Atticus indirectly teaches Scout about integrity when he insists that she attend school even though she doesn't like it. While the direct lesson is not integrity, the idea is still there that sometimes one must do things s/he doesn't like, just because it is right. He teaches Scout that what's right isn't always what is fun or easy or convenient.
Another instance is near the end when Jem and Scout are attacked. Atticus insists that if Jem is responsible for murder, that he be tried just like anyone else. He doesn't want favors to be given to his children, nor to allow Jem to live with that kind of thing on his conscience. (In the end, the reader finds out that there are other reasons why Jem should not be tried.)
Atticus shows his integrity throughout the novel; it is a primary point of the novel (there are those who demonstrate integrity regardless of their experience). To answer your question...
1. Atticus explains to Scout (in an indirect way) why it is important not to humiliate people when a neighbor pays his debt without money.
2. Standing up for what the Constitution says...'a fair trial'...Atticus takes on a difficult task when he decides to defend Tom Robinson. The community is against him, however in the face of adversity Atticus stands strong.
3. The moment that Atticus faces Tom Robinson's family after Tom was obviously killed has to be one of the most powerful examples of integrity. Here is a white man putting his vulnerability at the feet of a black family. This demonstrates the integrity not only of Atticus and the Robinson's but forces the reader to see that there just might be something out there larger than ourselves....perhaps a universal integrity that all humanity could benefit from.