There's a new normal for students heading back to class in the Washington area.

New teachers, new friends and new syllabuses warm from the printer are still there to greet them. But they'll also see basketball courts replaced by portable classrooms, leaving a lone hoop free; classrooms split into two by thin dividers; and in some areas, bigger classes.

Back to school
Aug. 20: Prince George's County Public Schools
Aug. 27: DC Public Schools, Montgomery County Public Schools, Loudoun County Public Schools
Sept. 4: Alexandria City Public Schools, Arlington County Public Schools, Fairfax County Public Schools, Prince William County Public Schools

Local schools are bracing for another year of seismic enrollment increases, which are outpacing officials' efforts to expand classroom space and build new schools. While Fairfax and Montgomery counties have been grappling with an additional 2,000 to 3,000 students each year for the last several years, the growth is beginning to overwhelm their neighbors, too. Arlington is looking to build its first new schools since the 1990s, while Alexandria City Public Schools will turn away some children from their neighborhood schools that are full.

"We've been working hard to get ready for this increase, but it has stretched our imagination, our capability of taking care of all these kids," Alexandria Superintendent Morton Sherman said.

Alexandria is expecting 12,800 students, a 3.1 percent increase over last year, and an estimate that the system will probably blow past: The school system has been expanding by 5 to 6 percent each year since 2008. Sherman said more families are choosing to stay in Alexandria than move to suburban Fairfax County once their kids reach middle school: "The urbanization of families is occurring."

But even without that influx from Alexandria, Fairfax is ballooning, too. Already the largest system in Virginia, the county is expecting nearly 3,000 more students this fall to bring the total enrollment to 181,510. Larry Bizette, a demographer for the school system, said an increase in minority families with higher birth rates has driven consistently large kindergarten classes for the past several years.

"A lot of these families will carry the preference for the number of children with them from wherever it is they're from and, in many cases, that tends to be higher in the Hispanic populations and the Asian populations than the traditional white populations," Bizette said. "After a generation or two, that preference becomes assimilated. [Trends going forward] depend on how much more foreign immigration we get."

Montgomery County -- where enrollment will soar above 149,000 with an additional 2,500 children expected -- is also seeing growth from the area's shifting demographics, spokesman Dana Tofig said.

Even Prince George's County and the District, where enrollment has been stagnant or declining, are struggling to accommodate students in certain areas. A renovation project to add seats at Laurel Elementary School is forcing its students to relocate to Greenbelt Middle School and Scotchtown Hills Elementary for the first weeks of the year.

In the District, where officials have been warning of school closings due to underenrollment, high-performing schools in Ward 3 are hundreds of students over capacity despite recent multimillion-dollar renovations. While high school class sizes are increasing by two students, other schools are losing play space. At Alice Deal Middle School, Councilwoman Mary Cheh says portable classrooms have taken over the basketball court.

"They tried to soften the blow by preserving a small space with one hoop," Cheh said.

Both Fairfax and Montgomery are relying on portable classrooms to accommodate students, in addition to brand new schools and renovations to add space at existing schools.

Fairfax is adding nearly 100 portables to bring the total north of 800. Tofig was not sure how many of last year's approximately 400 portable classrooms will remain at Montgomery's schools.

"We'd much rather have children in permanent buildings. It's just not possible to find an extra 2,500 ... permanent seats," Tofig said.

This article has been corrected to reflect that Arlington schools begin Sept. 4, not Sept. 6.