In chapter 3, after Scout has told Atticus about her difficult first day at school and her problems with the new teacher, Miss Caroline, Atticus reveals his best advice for understanding people.
You never really understand a person until you consider things from his point of view . . . until you climb into his skin and walk around in it.
This is advice that Atticus certainly lives by, and he strives to make his children understand it throughout the novel. There are many things that Scout is trying to understand—the new teacher, the hatefulness of the townspeople toward her father, Boo Radley, etc.
Harper Lee uses this idea to show Scout’s development at the end of the book. After Boo Radley has saved Jem and Scout, killing Bob Ewell in the process, Scout reconsiders her assessment of Boo. Previously, the kids had looked at him like a sort of secluded monster, to be feared. But in the last several pages, Scout says:
Atticus was right. One time he said you never really know a man until you stand in his shoes and walk around in them. Just standing on the Radley porch was enough.
Scout’s understanding of this advice demonstrates that she has grown, and that Atticus has been able to help her see that there is more to understanding people than just watching them and listening to them.