How does jack change over the course of the novel?

Jack initially spends time with Auggie only because Mr. Tushman asks him to. At the beginning, Jack is extremely conscious of his popularity and social standing at school, and says a lot of things he does not mean in order to be friends with Julian and his crowd. After he loses Auggie's friendship, though, Jack realizes where his priorities should lie. The moment when he punches Julian is a turning point for Jack; he establishes his allegiance at last, and rises above the petty fighting that Julian tries to start. Instead, Jack wants to do the right thing and be kind.