Mary Loveland is convinced the magic enrollment number for Lawrence elementary schools is 300.

Currently, 11 of the district’s 19 elementary schools have fewer than 300 children. The high is Deerfield School at 525, while the low is 39-student Grant School.

Grant will close in May because of low enrollment, leaving Riverside School, with 125 students, the smallest.

Loveland, a Lawrence school board member, said elementary consolidation had the potential to reduce each school’s grade-to-grade enrollment swing. Class sizes would become more predictable, which would improve chances of staffing schools in ways that best meet the needs of children.

“As long as you have a range … then you’re going to have trouble controlling it,” she said.

One advantage of setting the enrollment floor at 300 would be the elimination of combination classes, said Mary Rodriguez, the district’s director of human resources. That’s the academically questionable practice of mixing students of two grades together.

“Three hundred seems to be about where the difference is when there are combination classes,” Rodriguez said.

In a 1996 summary of 103 studies of school size, Kathleen Cotton of the Northwest Regional Educational Laboratory looked at how many students could be in a school before it was no longer considered small.

Definitions are flexible, she wrote, with some researchers putting the upper limit at 200 and others as high as 1,000.

Based on the review, Cotton estimated elementary schools are “right-sized” when they had between 300 students to 400 students.