More than 30,000 pupils will be affected by next Wednesday’s teachers’ strike which is expected to close every school in Brighton and Hove.
The majority of secondary schools in the city have already confirmed their closure.
Across the county it is predicted themajority of schools will also be hit.
Tens of thousands of pupils will get the day off as National Union of Teachers (NUT) members take to the picket line over pay, conditions and pensions.
Twenty-nine schools have confirmed they are to close across Sussex with many more expected in the coming days.
Phil Clarke, NUT union representative, described the decision to strike as “tough” for all teachers.
He said: “Teachers dedicate themselves to their jobs and striking is never easy. This action is about not only our own pay and conditions but also about the long term future of education for all children.
“Parents unfortunately put out by this strike should lay blame solely with the Government and Michael Gove.
“He refuses to enter into meaningful talks and leaves us with no choice if we are to make ourselves heard.”
There are an estimated 2,000 members of the NUT in Brighton and Hove alone.
Union representative Phil Clarke told The Argus he expected the “vast majority” to take part in the strike action, if not all.
He said: “Last time we held action on this scale I think there was perhaps one school left open in the city.”
TheNUThas around 3,000 members in East Sussex with around the same number again in West Sussex.
The national strike has been called over performance related pay issues, changes to pensions and what the union describes as excessive workload and bureaucracy.
They say teachers regularly work 60 hour weeks and as a result many “burnout” or simply walk away from the profession.
With regards to performance related pay, the union claims Michael Gove’s plans would see teachers working to better themselves rather than working to improve their school as a whole.
Changes to pensions has also been a contentious issue with teachers now set to pay more, work longer and receive less when they retire.
Mr Clarke added: “This is not the kind of action we take lightly.
“If the Government wants a good education system then it needs to start valuing those who make it, the teachers.”
Union members will hold a series of marches across the county on Wednesday.
In Brighton and Hove the main rally will be at the Brighthelm Centre in North Road at 11am.