If we look at what happens to Scout in terms of major events, we might make a list like this: 

- Scout goes to school for the first time.

- Scout witnesses the trial of Tom Robinson.

- Scout is attacked, along with her brother, and survives the attack.

Each of these occasions represents an event that has a big impact on the young girl.

In order to add to the other answers, I would say that all of the events that take place during the book demonstrate that Scout is learning how to look at the world and interact with it.  She learns about social class and race, but she also learns about humanity.  The events of the novel will shape the kind of human being she will become.

I was familiar with the movie version of To Kill a Mockingbird but only read the novel recently because so many people ask questions about it on eNotes. I have to confess that I don't think it is a great novel. Scout is an interesting character, but many of the others are very vague, even including Jem. There are a number of older white female characters who all seem alike--overweight, opinionated, lethargic, unattractive. Boo Radley is invisible for ninety-nine percent of the novel and has nothing to say when he does appear. The best part about the book is that, like "Tom Sawyer," it captures the feel of a sleepy Southern town.

Scout was strongly affected by many things in the book. I'll try to add a few that weren't mentioned in post #2.

1. Seeing Walter Cunningham, Jr. turn down Miss Caroline's offer of money to buy lunch.
2. Talking Walter Cunningham, Sr. out of trying to lynch Tom Robinson at that jail.
3. Going with Jem to read to Mrs. Dubose as she struggled to overcome her morphine addiction (although Jem and Scout didn't know about the addiction at that point.)

I would suggest that the important things that happen to Scout are revelations about life that Scout derives from multiple events.  For instance, Scout learns the dangers of prejudice when she and Jem judge Boo Radley only to be proved wrong again and again.  Boo seems to help Scout and Jem and he leaves them gifts.  By the time Tom Robinson is put on trial, Scout is less quick to judge people and certainly ready to learn another hard lesson.  Through this trial and the surrounding events, Scout learns the meaning of injustice.  She sees how Tom is treated and how unfair the trial turns despite Atticus's best efforts.  She sees the response of the townspeople as they try to take justice into their own hands and confront Tom in jail.  One of Scout's biggest lesson has to do with innocence or Mockingbirds.  Scout begins the story as an innocent child but ends with far more knowledge.  She sees the innocence in others like Boo Radley and Tom Robinson.