Jem Finch matures during To Kill a Mockingbird by Harper Lee. When the story begins, Jem is ten years old and beginning puberty. During the novel, Jem slowly develops the insight to understand many of the adult situations that his family faces.
In the beginning of the story, Jem enjoys the childish games of fantasizing about Boo Radley. Scout tells the reader that Jem becomes more and more moody as the story progresses. He thinks more; he shows more compassion; and he is appalled by the prejudice that rears its ugly head in his hometown. As incidents become more sinister, Jem begins to make decisions which separate him from the younger Scout and Dill.
Jem shows maturity:
On Scout’s first day of school, she runs into trouble with the new teacher Miss Caroline. Scout takes the responsibility of informing the teacher that she has made a mistake with Walter Cunningham when he does not have lunch money. The teacher offers to loan him some money. Scout tells her that Walter will not take the money because he cannot pay it back. Miss Caroline punishes Scout.
Because she receives a punishment, Scout knocks Walter down on the playground and begins to pummel him. Jem intervenes and stops the fight. Having heard Atticus talk about how the Cunninghams do not have money but always pay their debts in some way, Jem understands that Walter cannot help his family situation. He also knows that instead of fighting with him that he should be treated with respect. Jem invites Walter home to share their lunch since he does not have anything to eat.
Jem’s change in attitude toward Boo Radley portrays his movement toward maturity. When Boo begins to leave items in the hole in the tree, the children do not understand who left them. Slowly, Jem realizes that it is Boo’s way of communicating with them. Boo carves the children in wood; then, he mends Jem’s pants when he tears them. Miss Maudie’s house catches fire and during the excitement, Boo places a blanket around the shoulders of Scout.
Jem understands that Boo is not a dangerous character but someone who wants to befriend the children. Boo’s father cements the hole in the tree which was the connection between Boo and the children. Nathan Radley lies to the children and tells them that he did it because the tree is dying. Jem realizes that Boo’s father did it because he did not want Boo to be able to put things in the tree and communicate with the children.
“…Mr. Nathan put cement in the tree, Atticus, and he did it to stop us findin’ things---he’s [Boo] crazy, I reckon, like they say, but Atticus I swear to God he ain’t ever harmed us, he coulda cut my throat from ear to ear that night but he tried to mend my pants instead---he ain’t ever hurt us, Atticus---“
Jem finally knows that Boo is watching them and does not want to hurt them.
The night of the pageant Jem demonstrates his responsibility for his sister when he tries to protect her from the unknown assailant [Bob Ewell]. Standing up to the older man, Jem’s arm is broken during the scuffle. Eventually, both children are saved by Boo; however, Jem’s shows that despite his fear he will shield his sister from harm.
In the end, Jem’s behavior man reflects his father’s parenting and training of his children. On this night, Jem emerges as a mature adolescent who will become a fine young man.