To kill a mockingbird is a novel written from the ponit of view of Scout who is a precocious 6 or 7 year-old. She is smart, cute, funny, and different from most girls in her age group. She likes to "play with the boys", read with her father, and wear overalls. Her brother "puts up with her", but basically wants her to stay away from him while they are at school.
This story is about childhood innocence in full blossom. We see Jem, Dill, and Scout playing imaginary games about "Boo" Radley. They were stopped by Atticus (scout's father) because the games were unkind toward their neighbor. We see Jem being punished in a most peculiar manner by having to read to an elderly woman who almost always falls asleep during the reading session. We see Scout scolded for learning to read with her father who isn't a teacher.
At the children's appearance during the trial of Tom Robinson, we see that childhood innocence vanish. It may have had a deeper effect on Jem, but Scout's eyes are fully opened to the workings of the town, prejudice, and violent behavior.
Even though Scout loved her father in the beginning of the novel, her respect and admiration for her father grow as the trial progresses. Scout proves herself courageous when she confronts the lynch mob outside of the town jail where her father was keeping vigil.
Jem begins to see his father as a type of hero after he shoots a rabid dog with just one shot. Jem previously thought of his father as something of a cowardly man who would run from a fight. However, Jem learns that his father once was a crack shot with a pistol but chose to live a life as free from violence as possible. As a result, Jem gains greater respect for his father.
Since the children did not have a "mother", Calpurnia fills in nicely. She influences the children in a positive manner, dotes on them, brings them to church and shows them off to her "family". During a time when the town was basically rejecting the Finch family, throwing rocks at them, and calling them names, Calpurnia shows kindness, love and tenderness toward the children. It is through Calpurnia that the children are surrounded by the black community at the trial where they snuck in and sat in the black section because the "white section" was full.
At the very end of the story, they are no longer children. They were visciously attacked by Bob Ewell on their way home from a school festival. The Finch children were saved by "Boo" who ended up stabbing Bob Ewell, and carrying Scout home to her father.
From that point in the story, the children are no longer innocent. They are wise beyond their years when Scout says that to bring the public eye onto Arthur Radley would be like killing a mockingbird. They see the town and it's "ways" with grown-up sensitivities. Before the trial, the children knew the social strata well, but hot how and why things were the way they were. During and after the trial, they learned about prejudice, sexual violence, inter-racial relationships, revenge, and a myriad of other prejudicial flaws in our society.
I think that Scout learned from her father that there is a time and place to "rise up" out of what you "accept as normal" in order to do what is right.