How does Junior demonstrate he is gaining self-confidence in class?

When Junior first arrives at Reardan, he feels inferior to the other students because he is an Indian and they are white, but he slowly gains confidence. In the chapter "Slouching Towards Thanksgiving," he finally realizes that he is smart enough to challenge his teacher, Mr. Dodge. He says, "I learned that I was smarter than most of those white kids." When Mr. Dodge is speaking about petrified wood, Junior informs him that petrified wood isn't really wood. He then explains the process by which petrified wood develops. Mr. Dodge does not believe Junior until Gordy, a white student, backs him up. Eventually, Gordy and Junior become friends, and Gordy teaches Junior how to read and study. Their connection over learning and books also makes Junior more confident, as he knows he can match wits and learn with the person everyone identifies as the smartest kid at Reardan.