Thousands of teachers are set to walk out of classrooms over pay after the largest education union reached the threshold required to take strike action.
The National Education Union (NEU) had organised a ballot of 300,000 members in England and Wales, calling for a "fully funded, above-inflation pay rise".
Nine out of 10 teacher members of the union voted for strike action and the union passed the 50% ballot turnout required by law to take industrial action.
The NEU said the vote shows teachers are not prepared to "stand by" and see the education service "sacrificed" due to "a toxic mix of low pay and excessive workload".
But headteachers in England will not stage walkouts after the National Association of Head Teachers (NAHT) union ballot turnout failed to meet the legal threshold.
The NEU has declared seven days of walkouts in February and March, but it has said any individual school will only be affected by four of the days.
The first day of strikes will be on 1 February and more than 23,000 schools in England and Wales are expected to be affected.
The full list of proposed strike days is as follows:
• Wednesday 1 February: all eligible members in England and Wales
• Tuesday 14 February: all eligible members in England and Wales
• Tuesday 28 February: all eligible members in the Northern, North West, Yorkshire and The Humber regions
• Wednesday 1 March: all eligible members in the East Midlands, West Midlands, and Eastern regions
• Thursday 2 March: all eligible members in London, South East and South West regions
• Wednesday 15 March: all eligible members in England and Wales
• Thursday 16 March: all eligible members in England and Wales
In England, 90% of NEU teacher members who voted in the ballot backed strikes, with a turnout of 53%.
In Wales, 92% of NEU teacher members who voted in the ballot backed strikes, with a turnout of 58%.
Support staff in schools in Wales are also set to go on strike in the dispute over pay after 88% of balloted members backed action, with a turnout of 51%.
However, the NEU's ballot of support staff in schools and sixth-form colleges in England did not achieve the 50% ballot turnout required by law for action.
In a statement, Dr Mary Bousted and Kevin Courtney, joint general secretaries of the NEU, said: "This is not about a pay rise but correcting historic real-terms pay cuts.
"Teachers have lost 23% in real-terms since 2010, and support staff 27% over the same period.
"The average 5% pay rise for teachers this year is some 7% behind inflation. In the midst of a cost of living crisis, that is an unsustainable situation."
The statement continues: "The government must know there is going to have to be a correction on teacher pay. They must realise that school support staff need a pay rise.
"If they do not, then the consequences are clear for parents and children."
It adds: "It continues to be the aspiration of the NEU and its membership that this dispute can be resolved without recourse to strike action.
"We regret having to take strike action, and are willing to enter into negotiations at any time, any place, but this situation cannot go on."
In England and Wales, most state-school teachers had a pay rise of 5% in 2022.
But with inflation remaining at more than 10% and a cost of living crisis affecting households across the UK, unions have argued that such increases amount to a pay cut in real terms.
The government continues to insist that pay claims are unaffordable and is sticking to its belief that wage rises should be decided by pay review bodies.
The NAHT ballot result in England showed an appetite for taking industrial action amongst leaders, with 64% voting 'yes' to strike.
However, the legal requirement for turnout in England was not met, with votes counted for 42% of the union's membership - short of the 50% needed.
The union said it will consider re-running the ballot due to postal disruption.
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."
Last week, a ballot of members of the NASUWT teachers' union also failed to reach the 50% turnout threshold, although nine in 10 of those who did vote backed strikes.
The Children's Commissioner for England, Dame Rachel de Souza, said she is "disappointed by today's ballot results and the implications this will have on children's education".
She said in a statement: "I know the decision to strike will not have been taken lightly for any teacher, and the vote has been far from unanimous - but it comes in the wake of huge disruption from the pandemic and will add to the challenges already faced by so many pupils who are catching up on lost learning.
"I urge those choosing to take industrial action to take all possible steps to minimise the impact on children and families, by working to keep schools open for as many children as possible and with priority given to vulnerable pupils and those with SEND (special educational needs and disability)."
Education Secretary Gillian Keegan described the strike action as "deeply disappointing for children and parents".
"Talks with union leaders are ongoing and any strike action from one union will have a damaging impact on pupils' education and wellbeing, particularly following the disruption experienced over the past two years," she said.
"We have already met the unions' request for an additional £2bn in school funding, which will take real terms spending on schools to its highest level in history."
It comes as the wave of industrial action which has swept across the country for months is set to continue this week with members of the Royal College of Nursing (RCN) across England due to walk out on Wednesday and Thursday.