Parents are anxiously waiting to hear how schools in Kirklees will be hit by strike action.
A 24-hour walk-out is planned by the two biggest teaching unions on Tuesday.
Kirklees Council says the decision on whether to shut will be left to individual head teachers.
Many schools will leave the decision as late as possible.
The dispute is part of an on-going series of strikes across the country over changes in teachers’ terms and conditions.
The most controversial changes centre on performance-related pay and pensions.
Hazel Danson, joint secretary of the Kirklees branch of the National Union of Teachers (NUT), said she expected “the majority” of Kirklees schools to be affected.
“We are not taking this action lightly and we know it will cause disruption but we are left with no choice,” she said.
The union wants Education Secretary Michael Gove to negotiate over the changes but he has so far rebuffed their appeals.
Ms Danson said: “This strike action could be avoided if the Education Secretary behaved sensibly.
“Faced with his intransigence and his insistence on micro-managing the profession we have decided enough is enough.”
Ms Danson said under the changes teachers faced working longer before being able to take their pensions; would lose vital lesson preparation time; and could see school holidays altered.
“We are losing people from the profession in large numbers,” she said.
“We have a demoralised workforce. Teaching should be a wonderful job.
“It’s no wonder 50% of newly-qualified teachers leave the profession within five years.”
Ms Danson said some 80-90% of teachers were members of the NUT or the National Association of Schoolmasters Union of Women Teachers (NASUWT) and schools had to work on the basis that all members would take part in the strike.
“It’s a health and safety issue,” she said. “We expect the majority of schools to be closed or partially closed though some schools may see it as a badge of honour to stay open.”
A council spokesman said closure decisions were left to individual schools.
Parents should check for closures, as they would with snow, on the council website at www2.kirklees.gov.uk/com munity/education-learning/school closure/closurelist.aspx