If a Tree Falls at Lunch Period by Gennifer Choldenko

It's hard to describe this book. At first it seems like a school story about two kids with separate problems. Kirsten's parents are fighting, she's eating compulsively, and her best friend is hanging out with a nasty new friend. Walker is the new kid in school and it's tough to be one of the only African American kids at a fancy private school. The point of view alternates between the two characters and while they are friends at school they seem to lead unrelated lives. Then a major plot twist happens that changes everything. Kirsten and Walk have to re-think what they know about their families and themselves. It's definitely worth reading to find out what the secret is--this book is not what it seems at the beginning!