The Boston public school system is projecting that enrollment in preschool through the second grade will jump by nearly 1,000 students for the next school year — sending school officials on a massive hunt for 75 additional classrooms.
The projection — driven largely by an increase in disability diagnoses for toddlers, who by law must be given an education as soon as they turn 3 — follows a steady increase in enrollments in the lower grades over the last few years. At times, the surge caught school officials off guard and left a number of preschoolers at home waiting for seats as schools struggled to find space.
Next year’s projected increase — potentially more than twice as large as this year’s — could cause even more headaches for schools and families. Realizing this, the School Department is trying to get a head start on tackling the crush in enrollment, lining up new classrooms now instead of waiting until the spring or summer.
In a letter to all principals of elementary and K-8 schools on Thursday, the School Department asked each of them to identify at least one room that could be converted into an additional classroom, even if it means sacrificing space for computer labs or art, music, science, and other specialties.
Ann Waterman Roy, the department’s director for strategic planning, emphasized in an interview that the enrollment projections were preliminary and the actual enrollment would not be known until parents register their children for school, an annual process that kicked off this week.
“We want to prepare for the worst-case scenario and then scale it back if we have to,” Roy said.
School officials, however, said that they see the enrollment increase as a positive problem, a sign that parents have more confidence in the city’s schools after Superintendent Carol R. Johnson enacted a series of educational overhaul efforts in recent years.
The reasons behind the projected increase in enrollment mirror those of previous years, school officials said.
About half of the increase is due to more youngsters being diagnosed with autism spectrum disorder or other disabilities. During the two previous school years the School Department faced a backlog as it struggled to accommodate an influx of those students.
The reasons behind the rest of the enrollment rise are less clear, but school officials have several theories.
They said fewer students are leaving the system in the first and second grades, a sign that their parents are satisfied with the quality of schools. They also said more young families appear to be staying in the city. Parents in Beacon Hill and the Back Bay, for instance, have pushed for an elementary school in one of their neighborhoods.
Enrollments, however, are not rising across all grade levels. The School Department still sees a large departure of students as they reach the middle school years, especially as more charter schools open in the city.
In light of that, the department has asked principals to examine whether they can consolidate classrooms for students in grades 5 through 8, freeing up space for more students in the early grades.
The prospect, though, that programs for art, music, and science could end up on a cart instead of in a dedicated classroom could create an uproar among parents, said Myriam Ortiz, a parent and executive director of the Boston Parent Organizing Network, a grassroots organization.
“To ask principals to take away a speciality is not a good idea,” Ortiz said. “It’s not something that families would approve of.”
Ortiz said a better move for the School Department would be to re-open some of the elementary schools which were closed in recent years as the city sought to remedy anticipated budget shortfalls and an excess of empty seats.
Matthew Wilder, a School Department spokesman, said space for the arts and other specialities would be cut only as a last resort, adding that Johnson’s overhaul effort placed a strong emphasis on making sure all schools had equitable access to the arts.
But he said few closed schools remained mothballed. He said many have already been reactivated, including two that specifically serve elementary-school aged students, and just two buildings — one in Roxbury and another in East Boston — might be available for reuse.
The School Department has not developed a price tag for the projected enrollment increase. On average, it costs about $1,000 per student to outfit a new classroom with textbooks, supplies, and other materials. New classrooms would also likely require the hiring of additional teachers, but some of that cost could be offset by a decrease in the need for teachers in the upper grades due to declining enrollments.
At this early stage, the enrollment projections may not fully materialize.
Last April, for instance, school officials were bracing for a massive increase in kindergarten enrollment, after experiencing a more than 25 percent surge in applications during the first round of registration.
But the pace of registration dramatically slowed as the year progressed.
In the end, kindergarten enrollment was up by only 6 percent, according to a head count last month that tallied 4,471 kindergartners, an increase of 251 students from the previous year.
That increase, however, still led to the addition of about a dozen new classrooms in the western and northern parts of the city, where enrollments spiked.
“The good news is that we are attracting more families,” Wilder said.James Vaznis can be reached at email@example.com. Follow him on Twitter @globevaznis.