Janine Butler, a 28-year-old New Jersey teacher, knows something about out-of-control students.
One girl threw objects, threatened Butler with knives and tried to bite her. Another boy was "just rude, rude, rude," pulling down his pants and swearing at her. The final straw came when another student scratched and hit her.
Butler's students were barely out of diapers — 3- and 4-year-olds — and their public preschool in Trenton was not allowed to expel them.
"No one would do anything," said Butler, who eventually quit. "I felt alone."
Tantrums, aggression, biting and kicking are becoming increasingly common in preschool, according to child development specialists.
With bad behavior on the rise, so are preschool expulsions, according to a Yale University study published earlier this month.
Author Walter Gilliam, director of the Zigler Center in Child Development and Social Policy, told ABCNEWS.com that he didn't set out to study preschool expulsions. But when he was analyzing publicly funded prekindergarten policies at 3,898 schools in 40 states, he found expulsion rates three times higher than for older grades.
"Many teachers have anecdotally reported a perception of an increase in the rates over the past several years, but there are currently no scientifically collected data to confirm or deny this perception," he said.
Gilliam reported 6.7 expulsions per 1,000 preschoolers in the United States, compared with 2.09 per 1,000 for students in kindergarten through grade 12. In data collected from 2002-2004, rates ranged from zero per 1,000 students in Kentucky to more than 21 in New Mexico.
Private school expulsion rates were higher than for public school, and boys were four times as likely to be kicked out than girls.
Researchers identified a wide range of anti-social behavior — from cutting computer cords as a way to "liberate the mice" to hair-pulling. Biting was the most common offense.
"Nobody knows why," Gilliam said. "A lot of people blame parents. A lot of people blame the schools or an education system that pushed programs to preschool that are not developmentally appropriate. Now the stakes are higher in preschool."
Most public preschools must now submit accountability reports, according to Gilliam. "If behavior is a problem, in the past it was a nuisance, now it stands in the way of progress."
He concludes that expulsions set children up for educational failure and recommends better teacher training, smaller classes and greater classroom support from psychologists and social workers.
"We agree with the findings," said Don Owens, spokesman for the National Association for the Education of Young Children, who said many parents were afraid to talk openly with the media about their children's expulsions for fear of branding them.
"Expulsion should be the last resort, but unfortunately, it has become the first resort," he said.
Some studies show that aggression in preschool may be an indicator of delinquency and crime later on, according to a policy report by the National Institute for Early Education Research, which helped fund the Yale study.
NIEER's review of national research suggests bad behavior may be up for a variety of reasons: poor prenatal care, including drug use; family poverty and "negative parenting practices, such as harsh discipline and maternal insensitivity."
The school environment for these early learners may be to blame.