Suspended "between childhood and the adult world, pre-teens have been called the toughest to teach." Indeed, one can't touch middle school without hearing about "raging hormones." By all accounts, middle schools are a weak link in the chain of public education. Is it the churn of ill-conceived attempts at reform that's causing all the problems? Is it just hormones? Or is it the way in which grades are configured? For most of the last 30 years, districts have opted to put "tweens" in a separate place, away from little tots and apart from the big kids. Middle schools typically serve grades 5-8 or 6-8. But do these quasi-mad preadolescents belong on an island or in a big family, where even raging hormones can be mitigated by elders and self-esteem bolstered by little ones? Parents and educators have begun abandoning the middle school for K-8 configurations, and new research suggests that grade configuration does matter: when this age group is gathered by the hundreds and educated separately, both behavior and learning suffer.