Teachers have voted to take more strike action this coming June.
The National Union of Teachers vowed to step up their campaign as the row over pay, pensions and conditions continues.
The decision to take industrial action was made at their annual conference in Brighton.
National strikes will take place in the week beginning Monday 23rd June if "significant" progress is not made in resolving the long-running dispute.
The NUT have also said they will not rule out more than one day of strike action, with further action in the autumn still a possibility.
The strikes could leave thousands of school children across the country facing the prospect of school closures and disruptions to lessons.
The National Union of Teachers, the NUT, has voted to stage further strikes, starting with a national walkout in June in an ongoing bitter row over pay, pensions and conditions.
Members of the NUT and NASUWT are striking at Worthing High School over plans to make the school an academy.
The teaching unions say that staff were not consulted about the proposal and that they do not feel it is in the best interest of pupils.
A spokesperson for the school confirmed that 16 members of staff were taking part in the strike action.