Where and how are the characters' limits tested in "To Kill a Mockingbird"?
Talk about Dill's limits
Talk about Scout's limits
Talk about Arthur(Boo) Radley's limits
Talk about Atticus' limits
And the limits within Maycomb itself
Think of how Dill feels during the trial and the verdict. We see a lot about his true feelings here. His reaction toward the verdict shows his limit or capacity for handling prejudice.
Scout's patience is tested by her new teacher, with whom she butts heads on a regular basis. Her manners are pushed to the limit when she is around her aunt. Her bravery is pushed to the limit on the night of the pageant.
Boo Radley has stricter limits than most of the other characters at first. He does not even want to push himself to leave the house. So certainly, the night of the pageant, he pushes himself, too.
Atticus's patience with the other people in the town must surely be tested throughout the novel. It cannot be easy to be a man of integrity in an age where others are just finding theirs or ignoring it altogether. He shows great restraint when dealing with the members of Maycomb, whom he always treats as neighbors and friends even when he disagrees with their philosophies. And, of course, when they threaten his life.
The trial of Tom Robinson forces people to consider racial issues, whether they'd prefer to ignore it or not. Think of how the individuals in the town change as a result of this trial, and how that alters the personality of the town itself.