According to a just-released study by the Yale University Child Study Center, preschool-age kids are being expelled at an alarmingly high rate, up to 3x as frequently as K12-age kids.
The causes or reasons aren't clear, or rather, they're not interesting for reporters to bring up. Expulsion rates are 50-100% higher for black kids, boys, and kids in private (i.e., non-Headstart) programs. In other words, non-mandated, unregulated, no-government-standards schools are quicker to boot a kid, because they can.
But reading more closely, it turns out that when teachers have access to a behavioral consultant--someone to help them understand and deal with kids' antisocial behavior--the expulsion rate drops in half. Also, expulsions track closely with a teacher's reported job stress level.
So...you mean a preschool teacher's job is stressful, they're under-prepared and under-resourced, and it might take some training and preparation to ride herd on a roomful of 3-year olds? It took Yale eggheads three years to figure that out?
For what it's worth, the study didn't look closely at why kids were getting expelled, and standards vary by state for what constitutes expellable behavior. Kicking, hitting, and biting, I can understand. But then some well-meaning little kid gets tossed for cutting the school's computer cords "in order to 'liberate the mice'"?? Miss Crabapple, I think I need to see you in my office. Right now.
Preschool expulsions alarm experts [sjmercurynews.com, mentions Supernanny, how their state's kids aren't the problem]
Youngest students most likely to be expelled [wash post, VA says it doesn't have a problem, either; must be flaws in the data]
Gilliam, Walter S., PhD; Pre-kindergarteners Left Behind [found. for child dev., pdf. here's the report, see for yourself.]