Six schools were closed this week after teachers staged a series of one-day strikes against academies.
The joint industrial action - by the NUT and NASUWT - shut Chalvedon and Barstable schools in Basildon, Essex, on Tuesday. Both become academies this year.
Chris Keates, general secretary of the NASUWT, said teachers deeply regretted the disruption, but claimed they had to "make a stand".
Strikes also took place at four schools in Tamworth, Staffordshire, on Wednesday in protest at plans to close sixth forms and centralise post-16 education in an academy.
As a result, more than 70 jobs could go, pay rates were threatened and sixth form provision weakened, said the NASUWT
Woodhouse Business and Enterprise College will become an academy. The sixth forms at Belgrave High School, the Rawlett School and Wilnecote High School will close and pupils will be transferred.
Christine Blower, general secretary of the NUT, said neither parents, teachers nor the community wanted the proposed changes.
Peter Traves, director of children and lifelong learning at Staffordshire County Council, said the authority had reassured staff about their employment. Industrial action was now unnecessary, he said.
NASUWT members at Sussex Downs College in Eastbourne also staged strike action this week. Park College, a sixth form, was merged with Sussex Downs in 2003. The college wants to harmonise pay, which the NASUWT claims would lead to inferior contracts for teachers from Park College.