Some of Massachusetts largest school districts are asking the state to review plans to open their own all-virtual schools for students who want to learn remotely next fall.

Boston, Worcester and Natick are just a few of the 13 districts that have requested evaluations to open their own online school next September.

Boston Superintendent Brenda Cassellius said the proposed school in Boston could be an option for students with a health condition or who thrived during remote learning at home in the pandemic. It is not hybrid learning, she said, and does not require simultaneous teaching of online and in-person students.

“We want to be able to have a real online school as an option for families,” she said Friday on GBH News' Boston Public Radio.

State officials say virtual schools, at least as they have existed so far, have offered "mixed" outcomes. And the state's first-ever virtual school — Greenfield Commonwealth Virtual School — was placed on probation due to low academic achievement.

But a recent study by the RAND Corporation found that about 20 percent of school district administrators in the U.S. said their system had already started an online school, was planning one or considering it post-pandemic. Massachusetts districts seeking state review to open a virtual school in September also include: Attleborough, Brockton, Chelsea, Falmouth, Lowell, Peabody, Pittsfield, Quabbin Regional School District, Springfield and Westfield.

State officials say each district is proposing one virtual school, albeit with different grade configurations depending on the district. The proposals are under review.

Cassellius said she expects to receive its determination in early June.

They would not be the first virtual public schools in the state. Greenfield Commonwealth Virtual School, which opened in 2010, was put on probation from 2014 to 2019 due to issues around governance, enrollment, participation in MCAS, English language instruction and low academic achievement. When state officials removed its probation status, it required continued improvements. State officials said Friday that the school is still working to meet those conditions.

Earlier this year, state officials issued a memorandum urging caution to districts considering virtual options.

“It is important to note that, nationally, the performance of virtual schools is decidedly mixed,” it said.

The memo said the virtual model has yet to demonstrate consistently strong academic results for students.

“Before proceeding, districts should carefully weigh the extent to which a full-time district-operated virtual school would result in strong educational outcomes for students,” it read.

Justin Reich, director of the MIT Teaching Systems Lab and author of Failure to Disrupt: Why Technology Alone Can't Transform Education, says districts have learned that virtual schools can help a limited number of students who prefer it for a variety of reasons, including experiencing bullying or racism in in-person settings.

The schools also may serve elite student athletes who need flexible schedules to train or compete.

"Unfortunately, the virtual schools that we currently have in the Commonwealth are some of our lowest performing schools in the state," he said.

Ideally, he said, there would be one or two virtual schools offered by the state where resources could be pooled to offer top learning opportunities.

“A great city school system should have in the 21st century a really robust virtual option,” Reich said. “But all of the research and all the history on these programs tells us that it's really hard [to create].”

It's unclear whether the state review will allow the districts to create the virtual schools they have proposed, or how much support the state may provide. Reich says it would pose a significant challenge for a district to create a robust virtual school without state support or inter-district collaboration.