In this file photo from 2013, Sarah Cureton oversees an Earth science class of more than 30 students at Patriot High School in Nokesville, Va. After a decade of cost cutting, Prince William County schools have among the largest class sizes in Virginia. (Photo by Jahi Chikwendiu/The Washington Post)

Cash-strapped school districts across Virginia cut teaching and staff positions and crammed more students into classrooms during the Great Recession, as state and local funding fell off, leaving them with a huge deficit of teachers, according to a new report.

The Commonwealth Institute concluded that Virginia schools are now “missing” 11,200 staff members, including 4,600 teachers. That’s the number of additional staff members and teachers that would be working in Virginia schools if hiring had kept pace with student enrollment through the recession, when Virginia schools added more than 42,000 students to their rolls.

At the same time, the state has seen growth in the number of students who often need additional support. The report found a 39 percent rise in the number of students who are economically disadvantaged and a 33 percent increase in the number of students who enter school learning English. The homeless student population is up 73 percent, according to the institute’s report.

“What we’re seeing is dramatic upticks in student needs, and dramatic decline in school staffing,” said Michael Cassidy, president and CEO of the Commonwealth Institute, an independent group with a focus on the economic issues facing low- and moderate-income residents of Virginia.

Instead, many districts adjusted staffing ratios and hired fewer teachers and other staff members when enrollment boomed. In Prince William County, home to the state’s second-largest school district, school officials allowed class sizes to grow to the state maximum by allowing hiring to slack as more and more students flooded the district.

“In the face of state cutbacks, PWCS (and other school divisions statewide) were forced to increase class-sizes in order to maintain parent-desired programs and services,” said Keith Imon, a spokesman for the district. “As a result, class-sizes across much of PWCS are currently at or near state maximums.”

[Read more: Prince William class sizes are highest in Virginia, Washington region]

Researchers looked at staffing ratios before and after the recession and found that school divisions were no longer employing the same number of teachers, counselors, administrators and other school staff relative to the number of students they had. In schools across the state, it means that teachers are cramming more students into their classrooms, that counselors have bigger caseloads, and that overwhelmed administrators are passing clerical work on to teachers.

The Commonwealth Institute heaped criticism on the state, which cut funding to schools six years ago by adjusting the formulas used to calculate how much state funding school districts would get. Local funding makes up a huge part of school budgets, but many districts could not make up for the losses in state funding.

The report comes as Gov. Terry McAuliffe begins drafting the state budget. McAuliffe has pledged to make a greater investment in education.

Many school districts across Northern Virginia have fewer teachers per thousand students than they did in fiscal year 2008. Alexandria and Arlington, which had among the highest overall teacher-to-student ratios in the state in 2008, now are “missing” 181 and 147 teachers respectively. When it came to losses in teachers, Prince William County was among the hardest hit school divisions in the region. Even though the district never laid off teachers, Imon said hiring slowed. The Commonwealth Institute found Prince William is “missing” 367 teachers.

Loudoun, the state’s third largest district, is “missing” 832 teachers, the most out of any district in Northern Virginia.

The state’s largest district, Fairfax County, was the sole exception in the region, gaining 107 teachers. That number factors in changes in staffing in the tiny Fairfax City school district, which is entirely surrounded by and partially administered by the Fairfax County school district.

For teachers, this has meant rearranging desks to fit more students, less individual attention and, in some cases, cutting back on written assignments that take too much time to grade.

Charles Ronco, a math teacher at Stonewall-Jackson High in Manassas, said his classroom grew so crowded that students had to turn sideways to squeeze between desks. So two years ago, he finished up a project building custom benches and whiteboards for his classroom so that students could better fit in the space.

Ronco’s largest classes this year are two geometry classes for students who are learning English and are taught in a mixture of Spanish and English. At 32 and 33 students, Ronco said he has difficulty keeping students on task and getting them the individual help they sometimes need. The individualized help can be especially critical for his English language learner students, some of whom enter high school having been out of school for years or without a basic grasp of arithmetic.

“There’s a critical tipping point at right around 30 students,” Ronco said. “As soon as you hit that 30 threshold, the class dynamic changes immediately.”

Shannon Geraghty, who is on the board of directors of the Prince William Education Association, has taught government and history at Forest Park High in Woodbridge for a dozen years, and has seen her class sizes bloom from the mid-20s to consistently having more than 30 students. She said she feels unable to fully help her struggling students because she has too many students.

“I felt like when I first started teaching I could connect personally with students,” Geraghty said. “We just don’t have that today … and that really breaks my heart.”

This story has been updated.