Teachers across Nottingham struck on Thursday of last week against council plans to change the term structure. The strike affected around 60 schools.
The NUT union members say plans to move from a three-term year to a five-term one would be disruptive for workers and children.
It would mean a shorter summer holiday.
Workers say changes would also cause childcare problems for school workers with children.
The council has issued a Section 188 notice, meaning workers can be sacked if they don’t accept changes to their contracts.
Teachers plan to strike again next month.
The ATL union plans to ballot for strikes and NASUWT is holding an indicative ballot.