What were the challenges of growing up from the authors perspective?

"Atticus had promised me he would wear me out if he ever heard of me fighting any more; I was far too old and too big for such childish things, and the sooner I learned to hold in, the better off everybody would be." (Chapter 9)

Growing up means mixed signals. Atticus claims he'll wear Scout out if she continues to fight. :-)

Jem learns responsibility;

"Dill's eyes flickered at Jem, and Jem looked at the floor. Then he rose and broke the remaining code of our childhood. He went out of the room and down the hall. "Atticus," his voice was distant, "can you come here a minute, sir?"

Beneath its sweat-streaked dirt Dill's face went white. I felt sick. […]

Jem was standing in a corner of the room, looking like the traitor he was. "Dill, I had to tell him," he said. "You can't run three hundred miles off without your mother knowin'."

We left him without a word. (Chapter 14)

During the course of the novel both of the Finch children mature in different ways. Although Scout is our narrator (looking back), she's also just a little girl, and the events that surround this second grader serve to take away her innocence rather quickly.

Jem, on the other hand, is growing into a young adult. He's starting to understand the difference between good and bad, and he's also beginning to see things from adult perspectives. This new perspective serves to make him more aware of his own behavior and affects his own interactions with adults.