In chapter 22 of Harper Lee's To Kill a Mockingbird, what are six ways Jem shows maturity?

Chapter 22 of Harper Lee's To Kill a Mockingbird is the chapter right after the Tom Robinson trial ends. Jem has suffered a tough blow to his sense of justice, and he has probably lost a little bit of that childlike faith in humanity. As a result, Jem now see things from a more adult-like and mature perspective. One of the first things that Jem does is to cry angry tears. He cries for the injustice dealt to Tom Robinson and he suffers a deep sense of empathy for the guilty verdict. 

The next sign of growing up is that Jem is still worried about Tom Robinson the following morning. Children would go to sleep and wake up having forgotten the troubles of the day before, but Jem was still reeling. Atticus tells him not to worry because they still have an appeal to file.

Then Jem shows maturity telling Dill that he should not go running off without telling his Aunt Rachel where he's going. "It just aggravates her," he advises (214). This shows that Jem understands the plight of the adult and what Dill does to make things worse for himself. By giving Dill advice such as this, Jem shows that he understands the rule of cause and effect.

Dill continues talking about his Aunt Rachel at the Finch's breakfast table and Aunt Alexandra tells him to stop and that talking that way is "not becoming to a child. It's--cynical" (214). Rather than watch Dill get into an argument and thereby aggravate his Aunt, Jem immediately tells Dill to follow him outside. Thus, Jem takes his own advice, avoids an argument, and doesn't aggravate his Aunt.

Later at Miss Maudie's house, Jem gets to eat from the big cake as Maudie tries to help him understand Atticus and what happened the day before. Jem compares himself and Maycomb to having been a caterpillar in a cocoon (215); but now, he feels like what he thought were the best people in the world are not. This allusion is a profound insight for a twelve year-old to have. It shows that he is coming-of-age and understanding that things that seemed one way as a child are sure different once you grow up and experience the world a little more. 

The next thing Jem says that is very mature has to do with Dill's comment about him wanting to be a clown when he grows up. Dill's justification for wanting to be a clown is that he can laugh at people. Jem says the following:

"You got it backwards, Dill. . . Clowns are sad, it's folks that laugh at them" (216).

This final quote from Jem is the pinnacle of his maturity. Dill shows childlike misunderstanding of clowns and creates his own reality with his imagination. Jem, on the other hand, identifies the reality of a clown's job and accurately pinpoints it. Jem is using critical thinking skills just like an adult.