Gaithersburg would get a new high school — and an old high school in the North Bethesda area would reopen — under a sweeping construction plan unveiled by Montgomery County's schools superintendent.

The $1.8 billion proposal, which includes 30 building projects, comes amid record enrollment in the state's biggest school system.

Montgomery's enrollment surged to 161,936 students this year, a jump of 2,926 students from the previous year, preliminary figures show. It reflects a trend a decade in the making: Since 2007-2008, Montgomery has added more than 24,000 students.

The new high school in Gaithersburg would open on a 30-acre site in the Crown community, while Charles W. Woodward High School would open anew on Old Georgetown Road, where students now attend Tilden Middle School. Tilden would relocate to a new site it will share with Rock Terrace School on Tilden Lane.

Two elementary schools would be built in the Clarksburg area and another in Rockville. More than two dozen schools would get classroom additions, including a major expansion and upgrade at Northwood High School that would increase its capacity by 1,200 students.

Superintendent Jack R. Smith said the six-year plan required difficult choices, seeking to balance funding limitations with the imperatives of enrollment growth. Despite the $1.8 billion price tag, it "does not meet all the need," he acknowledged. "And that's kind of mind-boggling, frankly, but it's true."

It was Smith's first comprehensive capital improvements plan since taking the helm of the Montgomery County schools last year. It encompasses both new and existing projects, at a cost $74 million higher than the district's previous plan.

[In 2015: Montgomery, $1.72 billion pushed for school construction]

While largely aimed at addressing space needs, Smith's plan also has spotlighted a flash point: a changing approach to how officials assess and prioritize renovation projects in the 205-school district.

For years, Montgomery had a scoring system and kept a list that ranked renovation projects in order. That list is essentially gone, leaving some parents dismayed that after years of waiting for their children's schools to rise to the top, they no longer have a place in line.

Poolesville High School was among those long awaiting a remake. Parents and students testified about the need for years.

"We're very disappointed," said Kevin Schramm, a PTA leader who represents schools in the Poolesville area. "All of the sudden, they're changing the way modernizations are done. It sounds like it's become a more political process; that's the way we're interpreting it."

School officials say they have been rethinking how they approach renovations for years. In 2015, a county oversight office issued a report criticizing the system, saying it was based on outdated information, marred by errors and favored total reconstruction over renovation.

[Report prompts Montgomery to rethink its school modernization list]

District officials said they have not yet settled on a new method. But they say they have discussed the issue publicly at two board meetings and made presentations to parents over the summer.

They noted that five school renovation projects already in the works are continuing. They involve Seneca Valley High, Tilden Middle and three elementary schools: Luxmanor, Maryvale and Potomac.

Two countywide PTA leaders lauded the changing approach to renovation projects, saying the district is looking to do more with limited funding and is often targeting schools with both aging infrastructure and crowded conditions.

"There needed to be a more holistic way," said Laura Stewart, chair of the capital improvements program committee for the countywide Council of PTAs. "We see it as a positive step in the right direction."

Most of the 30 construction projects that are part of the plan involve classroom additions. Eleven existing elementary school addition projects are included, as are four new ones: at Cresthaven, Dufief, Ronald McNair and Roscoe R. Nix.

Classroom additions are also slated for six middle schools and four high schools. New projects would expand Silver Spring International Middle, Parkland Middle, John F. Kennedy High and Northwood.

Under the plan, an addition project at Col. E. Brooke Lee Middle School would expand in scope.

Jennifer Young, a PTA leader in Rockville, said the plan's "bombshell" is the proposal for a new high school in the Crown community, which she said appears to draw some of its enrollment from existing schools, including Richard Montgomery High.

Richard Montgomery had expected a classroom addition, which is not cited in the plan, Young said. "This is a real surprise and a shock to us," she said.

[School year opens in Maryland with enrollment surge in Montgomery County]

The growing student population in Montgomery County at first drove pressures for more space largely at the elementary level but more recently has hit middle and high schools, as large groups of students get older and move to higher grades.

School planners have said the increase is partly driven by birthrate trends and an influx of families with school-age children.

District officials say Montgomery has lacked money to keep pace with demand. Even with funding, the design and construction of a school takes at least four years, officials said.

School board member Patricia O'Neill said the growth has left the system facing choices that inevitably leave many families disappointed. The new plan is "a stab at it," she said, "but it doesn't meet everyone's needs." To do that, she added, "we need to win the lottery."

Smith's plan, outlined at a board meeting Monday night, will be discussed at a school board work session Nov. 2, with public hearings to follow, on Nov. 6 and Nov. 8. A second board work session is Nov. 14, with a board vote expected Nov. 27.