Fixing schools is slow. Superintendents and principals come up with plans. Guidelines are issued. Families are informed. Teachers introduce new lessons. Students follow as best they can, while years pass without big results.

Yet one category of change is much faster, often not in a good way. School districts have been experimenting with changes in rules to reduce the number of children sent home for bad behavior. They do that, and boom! Out-of-school suspension rates plummet, usually producing not applause but bitter disputes over racial differences and renewed disruption.

In a revealing analysis of California data, where out-of-school suspensions dropped more than 30 percent from 2013 to 2015, a Brookings Institution scholar found that changing the size and configuration of schools may be a better approach than changing the rules for who gets sent home.

“Breaking large schools up into smaller units may reduce suspension rates for all students — and especially for black students — but that means reassigning students to new schools,” said Tom Loveless, a nonresident senior fellow at the institution’s Brown Center on Education Policy.

He also suggested that switching from traditional separate elementary and middle schools to kindergarten-through-eighth-grade campuses — a change some D.C. public schools made in the past decade — could reduce suspensions of sixth-graders.

“A longitudinal study of New York City sixth-graders found that attending sixth grade in a middle school, as opposed to a K-8 school, produced a negative impact on achievement that began in the first year and extended throughout the middle school years,” Loveless said. “In surveys of both students and parents, respondents described middle school campuses as less safe, peer behavior as more immature and antisocial, and the overall quality of education as lower than in K-8 schools.”

By contrast, California appears to have achieved its sharp decline in out-of-school suspensions in two ways. It outlawed suspensions in some grades for “willful defiance,” which can range from yelling expletives to forgetting to bring a book to class. It also held meetings for perpetrators, victims, parents, teachers and educators to help students take responsibility for their actions — a method called restorative justice. Loveless said it was difficult to determine what had the greatest effect on suspension declines, but some educators complained that safety and learning suffered when fewer troubled kids were sent home. A petition signed by teachers at a Fresno high school said increased disruptions after suspensions were reduced were “unfair to students who come to school ready to learn and the teachers ready to engage them.”

Much controversy has been over black children continuing to be suspended out of proportion to their numbers even after suspensions have been reduced. Loveless noted that “the negative effects of disruptive students on rule-abiding peers almost certainly fall disproportionately on black students as well.”

Restorative justice and other discipline method changes may prove to be good alternatives to out-of-school suspensions, Loveless said, but “their efficacy has not yet been evaluated in rigorously designed evaluations.”

The same can be said for smaller schools, often associated with better school climates. “Large schools present management challenges that administrators in small schools do not face,” Loveless said. Troubled students may be lost in big schools. Some charter schools say that their smaller sizes explain in part their better results. Loveless showed that 38.2 percent of California’s largest schools, those with more than 1,300 students, have high suspension rates, compared with 22.4 percent with low rates, but there is not much research buttressing that connection, he said. The Bill & Melinda Gates Foundation failed to prove that reducing high school sizes leads to more achievement.

With so much unknown, school districts are unlikely to give smaller and better configured schools, the approaches Loveless finds most promising, much time to work. Sending disruptive students home seems the simplest solution to trouble at school, so it will remain a key method, even if it leaves children without adult supervision and falling further behind.