Sean Youngberg, a sixth-grade teacher at Graham Road Elementary School in Falls Church, visits the home of a student as part of a Welcome Walk before classes start. (Debbie Truong/The Washington Post)

About 280,000 students in Fairfax and Prince William counties returned to class Monday, marking the first day of the academic year in Virginia’s two largest school systems.

It’s the first year that school systems in Virginia can hold classes before Labor Day without having to apply for a waiver from the state. Gov. Ralph Northam (D) signed a measure rolling back the “Kings Dominion law,” which prevented schools from starting before the holiday to protect state tourism dollars.

School systems, including Fairfax’s, circumvented the provision in previous years by receiving weather-related or program waivers from the Virginia Department of Education. Several school systems in the region had elected to start classes ahead of the holiday even before the law went into effect in July.

Classes in the city of Alexandria and Arlington County are set to begin Sept. 3.

Under the new rules, school systems that begin before Labor Day must close the Friday ahead of the holiday weekend.

For teachers and students at Graham Road Elementary School in Falls Church, the return was brightened by the school receiving a $10,000 donation for supplies from Burlington Stores, which worked with AdoptAClassroom to support the school.

The money will provide relief for a school where 81 percent of students are economically disadvantaged and where officials said it’s not uncommon for teachers to dip into their own wallets to furnish classrooms with more reading materials and other supplies.

“This amount of money is going to be huge because it’s going to allow them to do all of the things that they hope and they dream,” Principal Lauren Badini said.

Teachers at Graham Road cheered the announcement on a sweltering afternoon, days before students were due in class. Later that afternoon, the teachers fanned across the Kingsley Commons townhouse development, stopping outside students’ homes to introduce themselves and welcome back the children.

Fairfax students return to the classroom with new technology — all high school students in Virginia’s largest system have been given school-issued laptops for the first time, part of a plan to put the devices in the hands of all students starting in third grade by 2023.

The 189,000-student school system also debuted a mobile app that parents and students can use to track the location of school buses.

In Arlington, Washington-Lee High School will reopen as Washington-Liberty High. Officials decided it was necessary to reconsider the place of Confederate Gen. Robert E. Lee in the school system after the deadly white-supremacist rally in Charlottesville in 2017.

The school system is also searching for a superintendent after Patrick K. Murphy announced plans to retire as Arlington schools chief, decamping for a job leading a school system in West Virginia.

Cintia Johnson, an assistant superintendent, will serve as interim superintendent until June 30 unless a schools chief is hired before then.

In the Arlington system, which faces overcrowding issues, Alice West Fleet Elementary and Dorothy Hamm Middle School will open this year. A new building called the Heights will house two programs — one for students enrolled in extensive special education services, another for students who want more autonomy and a nontraditional education setting.

Arlington is also opening a stand-alone public K-5 Montessori program.

Two new schools opened in the fast-growing Loudoun County Public Schools system, which started classes Aug. 22. Since 2007, the school system has added nearly 30,000 students and opened with 83,762 students for 2019-2020, according to school system figures.

The Loudoun system has built schools to keep pace with the growing population. This year, two new campuses opened in Ashburn — Independence High School and Waxpool Elementary School.