How has Jem changed since the beginning of the novel in To Kill A Mockingbird?

Throughout the novel, Scout has grown up and her perception of the world has changed. She is no longer scared of the book her father reads to her brother because she has experienced much more scary things in real life. She realizes that those around her are not always correct, due to Tom Robinson's trial and Boo Radley's newfound friendship. Both of these things are significant during the change from childhood to adolescence.