The main reason that Jem makes more rapid changes than Scout is the fact that he is of an age that allows him more logical analysis; Scout simply has not matured as much as her brother.
Two instances in which Jem's maturation is exhibited in his thinking is in the episode in which Atticus shoots the rabid dog and during the trial of Tom Robinson.
- Tim Johnson's shooting
In Chapter 10 Calpurnia calls Atticus about the dog going down the street in an erratic manner. When Atticus and Sheriff Tate arrive on the scene, they learn that the sheriff bows to Atticus as the better shot. So, Atticus kills the rabid dog, and the children learn that he was called "Ol' One-Shot" After Atticus returns to work, Jem "sat in numb confusion" and asks Miss Maudie about their father, wondering why he no longer goes hunting. She tells them,
"I think maybe he put his gun down when he realized that God had given him an unfair advantage over most living things."
Once they are at home, an excited Scout tells Jem that they have a great tale to relate at school; however, a more tempered Jem tells his little sister to keep quiet because Atticus obviously wants to keep his skill unknown to others. Scout replies, "Maybe it just slipped his mind," but Jem tells his little sister "It's something you wouldn't understand." Then, Jem stands and "jubilantly" tosses a rock and comments proudly, "Atticus is a gentleman, just like me!" From his assessment of this episode with the dog, Jem begins to understand his father's noble nature.
- The Tom Robinson Trial
During the trial Jem pays close attention to his father's actions and words. And, while Scout makes pertinent and insightful comments that display her having learned from observing Atticus at work on previous occasions, Jem's deductions go beyond the exhibition of observations by Scout. That he is logical is evinced in his comments about the evidence and Atticus's summation: "He made it as plain and easy as--well as I would have explained it to you," he tells his sister. When he talks to the Reverend Sykes as they all wait for the jury to return, Jem remarks, "Don't see how any jury could convict on what we heard--" But the minister warns Jem that juries do not side in "favor of a colored man over a white man," a fact that is not logical or dependent upon evidence. Later, after the trial, Jem cries because he does not understand how men would defy logic as they have. "It ain't right, Atticus." "No, son. It's not right," Atticus concurs.