Across Virginia, school divisions have been grappling with a decline in state education funding since 2008. But poor school divisions have born a disproportionate brunt of the cuts, according to a study by the Commonwealth Institute.

The study concluded that state funding drops were three times greater in the poorest school divisions than in the wealthiest ones.

“By cutting funding so deeply for the highest poverty school divisions, lawmakers are making it more difficult for schools to fully equip their students, threatening their economic prosperity and opportunity for years to come,” the study’s authors wrote.

The study underscores disparities in school funding that exist across the country, despite federal education spending that targets poor students and state funding meant to lessen the inequity. In Virginia, poor school divisions still get more state money per student than do wealthy divisions because the funding formula relies heavily on a school division’s ability to pay.

The study, released Friday, comes as Virginia lawmakers grapple with how to make up for a projected shortfall of more than $300 million.

“We would urge them to protect K-12,” said Mitchell Cole, a researcher with the institute and one of the authors of the study. “Look at the impact of what they’ve done ... thus far.”

The authors of the study divided school divisions into five categories, from poorest to wealthiest, based on 2008 U.S. Census data on poverty.

It then looked at state education funding since 2009, when funding started to drop. Between fiscal 2009 and 2013, the poorest set of school districts lost $1,490 per student in state funding. The wealthiest lost just $511 per student.

The authors pinned the disparities in funding cuts on the formula used to divide up the pot, called the Standards of Quality. Changes were made to the formula to cut state education spending. Those changes — including capping spending on social workers — appeared to hit poor school divisions harder.

Michael Cassidy, president of the Commonwealth Institute, said one of the state’s goals in education funding is to smooth out disparities between affluent and poor school divisions.

“When Virginia adopted the Standards of Quality formula, a key part of the reason that they did that was to deal with these issues of equity and the role that the state can play to equalize educational opportunity,” he said. “The changes that have been made to the Standards of Quality formula set that key goal back significantly.”