Last September, Ronan started at his fourth school in two years. He did well for a few weeks, but then moments of aggression reappeared. He’s been sent home twice for acting out. One more and Ronan will be expelled yet again.

“You would never know about the bad days on the good days because he’s so charming,” said his mother, Juliane Crump, as he played with blocks a few feet away.

Ronan is 3 years old, and the schools that have expelled him are local private preschools. He’s never seriously hurt another child, but he can be trying.

Crump’s experience puts her at the center of a raging debate: Is suspension or expulsion the right punishment for children who misbehave in school at any age, or is it just hampering their education?

RELATED: State bill seeks to reduce school suspensions for defiance

In March, the U.S. Department of Education released statistics showing that 5,000 preschoolers nationwide were suspended at least once during the 2011-12 school year. Half of them were suspended more than once.

That’s not even the complete picture; those numbers only include children at public schools, not private preschools or home-run childcare centers like the one Ronan attended.

And one national expert doubts the federal numbers are accurate, even for public-school-based programs.

Some of the largest school districts in California – Los Angeles, Santa Ana, Oakland, San Francisco  – showed zero preschool expulsions in the 2011-2012 federal data, the first year the federal government required school districts to report it. The state doesn’t require school districts to break out expulsion reports by grade.

L.A. Unified school district has an unwritten policy against suspending or expelling preschoolers, said Maureen Diekman who runs the district’s early education programs.

“When there’s a child with challenging behavior, we work with the family and work to find out how best to meet that child’s individual needs,“ she said.

California Head Start officials also said they enlist the help of parents and guardians to curb behavior issues, rather than expel children.

Yale professor Walter Gilliam doesn’t believe that California’s preschools are not suspending or expelling kids. When he set out to conduct the first major national study on preschool expulsion in 2005, he said officials told him they had policies against it, too.

But when his research team surveyed teachers directly, they found that – whatever schools’ policies may be — teachers were indeed asking problem preschoolers to leave. Often.

“Pre-kindergarten children were being expelled at [a] rate well over three times that of K through 12 combined,” he said.

California is well above the national average

In California, the expulsion rate was 7.5 children per thousand preschoolers, well above the national average of 6.7 per thousand. That made it the 16th highest state in the nation for preschool expulsion rates. 

And, just like in upper grades, both Gilliam’s study and the new federal data show suspension rates are higher for African-American children than students of other races – even in preschool.

For 2011-2012, the federal data shows half of the preschool children suspended were black, even though black children made up only 18 percent of all preschoolers.

“Unconscious bias infects our relationships with children all the way down to very young children in preschool,” said Daniel Losen of UCLA’s Civil Rights Project, which opposes what he considers the overuse of suspension in classrooms.

Tuppett Yates, a professor at UC Riverside, agreed. While studying play as a marker for kindergarten readiness, she stumbled on something else. Her research team saw no notable difference in the way children of different races play, but teachers rated the children very differently depending on their race.

Yates’s 2013 study found that creative and expressive white children were liked by teachers and rated by them as being ready for school.

“For black children, it was exactly the opposite,” she said. “Those creative, expressive black children, the teachers saw as greater sources of conflict and less prepared for transition to formal school.”

The study found those opinions consistent among teachers of all races. Yates said her study should be a warning to teachers to check unconscious bias.

Like Losen at UCLA, Yale’s Gilliam thinks preschools should work with kids who are having behavioral problems, not kick them out – particularly at the preschool age, which is when kids are supposed to start learning how to behave.

During a recent study in Connecticut, he found significant reductions in behavioral issues in classrooms where preschool teachers had access to support services or a coach.

It’s something other preschools across the country are trying.

 “When a coach goes into a classroom, we’re observing a little bit of everything: social interactions, language development, concept development,” said Astrid Feist, a coach with Los Angeles Universal Preschool. (LA UP is a sponsor of KPCC’s education coverage.)

She introduced Norwalk preschool teacher Stefanie Servin to a strategy called “conscious discipline” when Servin struggled with a disruptive student at the beginning of the school year. The technique teaches kids to name their feelings, then use yoga-style breathing to calm down.

Servin said she uses the strategy constantly and her classroom is a much calmer place.

"It's trying to get their impulses in control," she said, "so that as they get older they know there are appropriate outlets for them."