Schooled by Gordon Korman
This book features Capricorn Anderson, a young boy that has lived his 13 years sheltered on a commune farm with his non-traditional grandmother. An accident leaves Cap temporarily at a foster home and at his first public middle school. The middle school students do their best to make things difficult for Cap, but in the end his peers may be the the ones that learn the most.
I thoroughly recommend this book to 3rd through 5th graders.