What is the exposition of the book Speak by Laurie Halse Anderson?

Expositions are used to introduce background information about events, settings, and characters.

The exposition of the book Speak introduces readers to the narrator.  Her name is Melinda Sordino.  She is riding on the bus on her way to her first day of high school at Merryweather High.  That tells readers her approximate age.  Readers also learn that Melinda is not well liked by just about everybody.  Something happened at the end of the previous school year, and Melinda is the cause of that; therefore, everybody treats her like a pariah.  Not even her former friends want anything to do with her.  The only student that does want to actually talk to Melinda is a student named Heather. Readers also learn that what happened a few months ago was that Melinda called the police and had a party shut down.  That's why the students are holding a grudge against Melinda.  Lastly, the exposition includes details that something else really bad happened to Melinda at the party.  It's why she called the police, and she desperately wants to tell people about it, but she doesn't know how.