It's Yr Life — Tristan Bancks

In this expository young adult novel, Sim and Milla are an unlikely pair for a school assignment and don't get along -- until it becomes a matter of life or death

Sim in Australia and Milla in Los Angeles don't seem to have anything in common. Sim lives in a foster home for kids who don't know where their parents are, and Milla lives in a mansion with her family, including her big shot movie producer dad. So when they're forced to email each other for a school assignment, this is one pairing that seems doomed to fail from the start. But soon the two can't stop emailing each other. Why? Secrets. What did Sim find in a dumpster that has him running scared? Whose footprints are outside Milla's window, and what can she do to fix her screwed -- up family before something terrible happens?