Last week, the Boston Globe ran an editorial about charter school funding with an eye-catching and controversial headline: "Charters aren't draining district school funding."

It's a subject that's often been debated during the battle over Question 2, a ballot question that would—if passed—lift the cap on the number of charter schools permitted in the state.

Paul Reville, former state Secretary of Education and professor at the Harvard Graduate School of Education, joined Boston Public Radio to explain the nuances behind school spending. He says that while per-pupil spending at mainstream public schools has not decreased because of charters, it's also important to think about funding on a school-by-school basis.

"The facts that are pointed out in that study are undeniable," Reville said. "On a per-pupil basis, spending per pupil in the district and in charters is rising at roughly the same level, so you can't make the case that it's a dramatic drain on per-pupil spending."

But Reville said that when mainstream schools lose students, they are required to adjust their budgets accordingly and do business less expensively than they were able to do before, which often results in the loss of programs.

"Had that money remained in the system [and] had those students remained in the system, the rate of spending would have gone up and the system would have been able to put forward more programs and more variety for the programs than they are able to with fewer students," Reville said.

Mainstream public schools would argue that the marginal savings associated with losing a student are not nearly as much as the marginal costs associated with losing a student—which Reville says is probably true.

"There's less variety of programs in Boston than there might be if they had more students there and therefore more overhead to fund programs," he said. "But at the same time, you can't make the case that on a per-pupil basis they're spending less than charter schools."

To hear more from Paul Reville, tune in to Boston Public Radio above.