The story is told as a first person narration by Jean-Louise (Scout)Finch. Scout is telling the events of her childhood.
Scout is only six at the beginning of the story, but the tale is actually narrated by Scout as an adult, reflecting on the events of her childhood. There is a great advantage in this style as we the reader are given the child's perspective on events which help us see the injustice of the racist views of the time much more clearly, and we become involved on Atticus' education of his daughter to appreciate people for who they are. When Scout has had her terrible first day at school, Atticus helps her to see how to consider the views of others-
“First of all,” he said, “if you can learn a simple trick, Scout, you’ll get along a lot better with all kinds of folks. 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.”
The narrative style is not restricted to childish language and expression, however, as Scout is reminiscing as an adult. Harper Lee's style therefore gives the reader the advantage of an adult narrator with a child's innocence and clarity.