Montgomery County’s newest school, Flora M. Singer Elementary, opened for the first time Monday in Silver Spring, adding much-needed classroom space to a rapidly growing school system that was already the state’s largest.

School officials project enrollment to top 149,000 students this fall, an increase of about 10,000 since 2008 and 2,500 since last year.

Shirley Brandman, president of Montgomery’s Board of Education, said the enrollment is the largest in county history.

The opening of Singer provided relief for Oakland Terrace Elementary, which schools spokesman Dana Tofig described as “terribly, terribly overcrowded.”

Singer Principal Kyle Heatwole said the new school was “critical to this neighborhood and this community, absolutely.”

Oakland Terrace was so crowded, Heatwole said, that kindergartners were moved to a satellite campus at Sligo Middle School. Heatwole said Singer’s opening was intended to reduce the student population at Oakland Terrace by about half.

Schools Superintendent Joshua P. Starr said about 750 teachers were hired countywide over the summer to help keep class sizes manageable. In addition, Starr said the county plans to build more schools in the near future.

“I wouldn’t say we’re bursting at the seams because I think that our staff do a pretty fabulous job of managing it,” Starr said. “Some schools may feel more crowded than others. It’s a challenge, but it’s one we can meet.”

In Maryland, classes also started Monday for students in Charles, Frederick and Howard counties, with a phased launch in Anne Arundel County. Baltimore County was stunned on the first day of class when a teenager was shot and critically wounded at Perry Hall High School, and another teenager there was taken into custody.

School also opened in the District and in Loudoun County, with most Northern Virginia systems scheduled to open Sept. 4.

Montgomery opened its first public charter school: Community Montessori in Kensington. Paint Branch High School in Burtonsville reopened after a top-to-bottom overhaul.

The first day at Singer began smoothly — and with only a few tears at drop-off — as nearly 500 children bustled inside gleaming hallways and scuff-free walls.

The school was named for Flora Mendelowitz Singer, a longtime Montgomery teacher who died in 2009. She escaped Nazi-occupied Belgium as a child and later taught students about her life as a Holocaust survivor.

Children sporting fresh haircuts and Batman and Tinkerbell backpacks jittered over the tile floor toward their classrooms.

The school is equipped with new computers and state-of-the-art interactive whiteboards in every classroom, a geothermal heating and cooling system, and an innovative green roof with plants growing on top.

“The facilities are really impressive,” said Tim Kay, 42, father of a first-grader named Abigail. “Obviously, you want your kid to go to school where everything is the best of the best.”

Heatwole said he plans for the teachers to use “our technology as a resource for learning.”

The students, Heatwole said, “really need to be proficient in the use of technology as they grow up and later become part of the workforce.”

Picture windows illuminated the cafeteria, where students gathered before the opening bell. Outside, the jungle gyms, monkey bars and slides awaited students for recess.

“Its beautiful, nestled in the woods,” said Deborah Beck, Kay’s wife and Abigail’s mother. “The kids will eat lunch looking out at nature.”

Wearing a bright pink dress and matching pink backpack, Abigail, 6, said she was most excited about art class, where she wants to “paint a picture.”

Kindergartners preparing for their first day met at an outdoor playground before saying goodbye to their parents.

Heidi Bryan, 34, said her son Asher Clark, 5, was “itching to get out the door” that morning. “He said ‘C’mon mom, I’m gonna be late.’ ” Bryan said.

Nikolaos Arvanitakis, 5, woke up at 6 a.m., he said, “because I was excited.”

His mother, Nathalie Arvanitakis, 40, said: “I can’t believe he’s 5 so fast. I’m not ready to get rid of him.”

Joshua Rovner, 37, held his daughter Sara’s hand as they walked to the playground. Rovner knelt on the blacktop to give her a hug before she walked inside. Tears streamed down his cheeks and onto her shoulder.

He had come prepared with a pocketful of tissues from home.

“I’m very proud of her,” Rovner said. “I feel she’s going to do great.”

Smiling, Sara provided her father with some reassurance.

“See you tonight,” she said.