Fed-up teachers in England and Wales will stage a series of walkouts over pay in February and March.
The National Education Union announced national strikes on February 1 and March 15 and 16, as well as regional action on four other days.
More than 23,000 schools in England and Wales are expected to be hit by the first walkout, with heads given guidance on switching to online lessons if they haven't got enough staff to keep schools open.
In echoes of lockdowns, schools are being urged to prioritise vulnerable kids and the children of critical workers on strike days - and then pupils preparing for formal exams.
Teachers are angry about the Government's 5% pay offer for most experience staff, which amounts to a 5% real terms wage cut due to high inflation, according to the Institute for Fiscal Studies.
Unions have also warned about persistent staffing problems. The Government missed its own target for recruiting new secondary teachers by 41% last year.
Mary Bousted and Kevin Courtney, joint NEU general secretaries, said: "We have continually raised our concerns with successive education secretaries about teacher and support staff pay, and its funding in schools and colleges, but instead of seeking to resolve the issue they have sat on their hands.
"It is disappointing that the Government prefers to talk about yet more draconian anti-strike legislation, rather than work with us to address the causes of strike action."
But Education Secretary Gillian Keegan called the strike vote "deeply disappointing" and argued it "will have a damaging impact on pupils' education and wellbeing".
Here's what we know about the strikes so far.
How many teachers are going on strike?
The NEU balloted more than 300,000 teachers and school staff in England and Wales for strike action, which was backed by nine out of 10 members.
But the union has not published an exact number on how many teachers will take industrial action.
There were 563,831 full time teachers in the UK in the 2021/22 academic year, the latest official data shows.
Not all members will walk out at the same time.
How many schools will be affected?
Some 23,400 schools in England and Wales will be hit by the first day of strike action on February 1.
There will be seven days of rolling strikes. Some will be across England and Wales while others will only affect some regions in England. In Wales there will be a separate strike on February 14.
Individual schools will only be affected by four walkouts, the union says.
Will schools close?
The Government has urged schools to take "all reasonable steps to keep the school open for as many pupils as possible" - but the decision to shut lies with heads. In academies, the academy trust will decide whether to close.
During the last national teachers' strike in 2016, 11% of schools shut their doors and 20% were partially closed.
Heads are being told to prioritise vulnerable kids, the children of critical workers and those sitting exams if they have to restrict numbers of pupils in the classroom.
Support staff can provide supervision for lessons or oversee other activities but rules say classes must be taught by qualified teachers.
There is no limit on how many pupils over 7-years-old can be looked after by a teacher. For nursery-age kids, there must be one teacher per 13 pupils.
Infant classes must have a teacher per 30 pupils.
School volunteers with criminal records checks can help with supervision during strikes.
Will lessons go online?
New Government guidance issued on Monday said schools should try to deliver remote learning if they have to restrict pupil attendance.
Schools can revert to Covid-era online lessons if this happens.
Could there be more strikes?
The NAHT, which represents heads, has said it's considering reballoting its members after missing the 50% turnout threshold.
Paul Whiteman, NAHT general secretary, said: "It is incredibly frustrating that anti-trade union and anti-democratic legislation compelled us to conduct the ballot by post during a period in which the management of the Royal Mail refused to take action to ameliorate the disruption to the postal service."
He added: "We have to conclude that our democratic process has been compromised by factors outside of our control."
Another education union, the NASUWT, has said it will continue its campaign on pay and expects to announce plans "shortly" for further balloting of members, after a vote last week failed to reach the 50% turnout threshold.
NEU Strike dates in full:
Wednesday 1 February 2023: all eligible members in England and Wales.
Tuesday 14 February 2023: all eligible members in Wales.
Tuesday 28 February 2023: all eligible members in the following English regions: Northern, North West, Yorkshire & The Humber.
Wednesday 1 March 2023: all eligible members in the following English regions: East Midlands, West Midlands, Eastern.
Thursday 2 March 2023: all eligible members in the following English regions: London, South East, South West.
Wednesday 15 March 2023: all eligible members in England and Wales.
Thursday 16 March 2023: all eligible members in England and Wales.
