Massachusetts’ largest teachers unions strategy for urging fully remote learning in the state this fall hit a snag when a teacher strike in Andover was ruled illegal by the state’s labor board, after the union instructed teachers not to enter school buildings for a staff training last week.

Paul Reville told Boston Public Radio on Thursday he agreed with the labor board’s decision, though acknowledged that there is no unified front on either side of the issue.

“There’s a lot of tension now between the unions’ understandable and justifiable role in protecting their members’ health and interests, and school districts pushing hard to reopen school, with a lot of parents feeling they want to see their children back in school,” he said.

State law prohibits public employees from striking, and the labor relations board determined that the union overstepped its authority when it tried to unilaterally dictate where teachers perform their work.

“I’m looking, I know a number of people are looking for flexibility, both from management and labor, in getting to a set of agreements that takes into account the needs of children and families in this moment,” he said.

The ruling comes as a number of districts are still negotiating how to start school this fall.

Reville is former Secretary of Education and a professor at Harvard University’s Graduate School of Education where he also runs the Education Redesign Lab. His latest book, co-authored with Elaine Weiss,  is “Broader, Bolder, Better: How Schools and Communities Help Students Overcome the Disadvantages of Poverty.”