Tens of thousands of teachers across England and Wales will strike over three days this week in the long-running dispute over pay.
Teachers will walk out across the north of England on Tuesday with the majority of schools expected to either restrict access to some pupils or fully close, the National Education Union (NEU) has said.
Education Secretary Gillian Keegan has called strike action “unforgivable”, adding that children deserve to be in class, especially after the pandemic.
Teacher members of the NEU are set to strike in the Midlands and eastern regions in England on Wednesday, and further walkouts will take place across Wales and the south of England on Thursday.
Kevin Courtney, joint general secretary of the NEU, told the PA news agency: “I think across the three days we will have 200,000 members taking strike action.”
The country’s largest education union has had 50,000 new sign-ups since the strikes were announced six weeks ago, he added.
Speaking ahead of the strikes in the north of England, Mr Courtney said: “I think a majority of schools will be affected by the dispute. Some of them with full closures and many more with partial closures.
“Some secondary schools will be completely closed, others will have particular year groups in and a similar pattern in lots of lots of primary schools.”
Picket lines will be mounted outside schools in regions including the North West and Yorkshire and the Humber on Tuesday, and rallies will be held in Manchester, Leeds and Newcastle.
Some parents will be forced to take leave from work, or arrange alternative childcare, as a result of the regional walkouts across three days this week.
In a message to parents, Mr Courtney said: “We really do sincerely apologise for the disruption to their children’s education on our strike days, and to the disruption to their working lives and home lives.
“But we do believe we’re taking action with a moral purpose of trying to get the Government to invest in their children’s education.”
Last week, Ms Keegan invited the teaching unions to “formal talks on pay, conditions and reform” on the condition that NEU strikes were suspended.
The NEU has called on the Education Secretary to drop preconditions to talks and instead make a “serious” offer on pay to avert national walkouts from taking place across England and Wales on March 15 and March 16.