Certainly, the two major events of To Kill a Mockingbird are the trial of Tom Robinson and Bob Ewell's attack of Jem and Scout and their rescue by Boo Radley. Other important events include:
- Scout's first day at school.
- The children's abortive attempt to get a glimpse of Boo Radley on the night that Jem loses his pants.
- The various gifts that are found in the knothole of the Radley oak tree.
- The unseasonal snowfall which precedes Miss Maudie's house fire.
- Atticus shooting the rabid dog and the children learning of their father's former nickname.
- Jem's attack on Mrs. Dubose's camellias and her later death.
- Scout and Jem joining Calpurnia at her church.
- The death of Tom Robinson.
This may be a matter of opinion, because every teacher likes to focus on different aspects of a novel like this one. When I take a look with my students, I find the book to demonstrate innocence in several ways, but three in particular.
1. There is this storyline of Boo Radley throughout the book. From the beginning, the children find him to be the persona that the town believes: a phantom. The mystery of his character seems to turn out to be different than their original suspicions. In fact, he ends up being a hero.
2. The story of Tom Robinson's accusation and our experience of his innocence as facts are revealed throughout the trial and beyond seems to be a second major purpose of the novel.
3. Finally, the loss of the children's innocence as they discover the problem of humanity's judgement and Maycomb's prejudice occupies the majority of the book. This is important because these children seemed to live a life in which they can learn from the mistakes of the generation before them.
Your teacher may be looking for something different, but in short, this is one way to divide the book into 3 major happenings.