Since there is no specification on which types of quotes are desired, perhaps a mixture of quotations that give thematic meaning and character development will assist the student.
Of course, there are the often-repeated quotations from Atticus Finch about killing a mockingbird being a sin and the necessity of climbing into another person's "skin" in order to understand him/her. However, there are many others that are certainly significant. Here are three with explanations accompanying them along with the chapter in which they are located.
1. When Scout asks her father why he has taken Tom Robinson case, he tells her that this case "goes to the essence of a man's conscience." Still, Scout objects, saying that "most folks seem to think they're right" in their opinions about the case. Atticus then replies,
"They're certainly entitled to think that, and they're entitled to full respect for their opinions...but before I can live with other folks I've got to live with myself. The one thing that doesn't abide by majority rule is a person's conscience." [Chapter 11]
Here Atticus imparts an important lesson to his daughter: One must answer to his/her own conscience. As Ralph Waldo Emerson urged, man must be self-reliant because society is often in conspiracy against him. Atticus is against a conspiratorious society that wishes to condemn Tom Robinson when he is really innocent. Knowing full well that Tom has done nothing wrong, Atticus, as a man of integrity, must defend him.
2. After Tom Robinson testifies and his testimony is viciously turned upon him, placing guilt upon him for feeling sorry for Mayella Ewell, Dill begins to cry in reaction to Mr. Gilmer's brutal cross-examination of Tom. So, Scout takes him outside where Mr. Dolphus Raymond overhears Dill's explanation of why he began to cry. He tells Dill that he understands and adds,
"Things haven't caught up with that one's instinct yet. Let him get a little older and he won't get sick and cry...."
When Dill asks him what he means, he replies,
"Cry about the simple hell people give other people--without even thinking. Cry about the hell white people give colored folks, without even stopping to think that they're people, too." [Chapter 20]
This statement parallels that of Atticus that a person should try to perceive things from the point of view of others. In addition, it points to how adults have hardened their hearts to others and are unconcerned about the hurt they cause in their gratuitous malice.
3. After the trial and unjust conviction of Tom Robinson, Jem asks his father how such a verdict could be reasonably reached. Atticus tells his son,
"...you saw something come between them and reason....There's something in our world that makes men lose their heads--they couldn't be fair if they tried....[Chapter 23]
Atticus, of course, speaks of the bias in men's hearts. Later, in his editorial after the trial, Mr. Underwood underscores what Atticus as said, depicting the "something" as the "secret court of men's hearts." [Chapter 23]