Breaking Rank by Kristen Randle (2002, Paperback, Reprint)

Thus does the Clan speak

To Baby, the outside world is a cold and lonely place. The silent, enigmatic group that calls itself the Clan is his home, and he has been scorned and feared by classmates and neighbors. Like the rest of the Clan, he has never before participated in school. It's up to Casey to see to it that Baby isn't alone when he's the only Clan member to be placed in honors classes. But what Baby is doing threatens Clan and non-Clan alike, and it isn't long before Baby's and Casey's familiar worlds are shattered.