Teachers in England have announced two more strike dates after rejecting the government's latest pay offer.
In total, 98 per cent of National Education Union members voted to turn down the deal, the UK's largest education union said.
Teachers will walkout on Thursday, April 27 and Tuesday, May 2.
However, exam classes will not be interrupted.
The move is a major blow to Rishi Sunak’s government, which had offered a one-time, £1,000 payment to teachers for the 2022-2023 tax year, as well as a 4.3 per cent rise next year.
The NEU said the "insulting" offer was not fully funded and around half of schools would need to make further cuts to cover the pay rises.
"This resounding rejection of the government's offer should leave (education minister) Gillian Keegan in no doubt that she will need to come back to the negotiating table with a much better proposal," NEU joint General Secretaries Mary Bousted and Kevin Courtney said in a statement.
"The offer shows an astounding lack of judgement and understanding of the desperate situation in the education system."
Dr Bousted told the BBC Radio 4 Today programme on Monday: "This is a profession which of all the professions having disputes with the government has lost in comparative terms the most pay since 2010."
She said the offer does "virtually nothing" to "start to re-correct" the "long decline" in teachers pay in real terms and claimed the government is using the "tactics of the bully boy" by saying it will remove the offer if it is rejected.
She added: "These strikes... are an indication of the despair that teachers feel about the lack of understanding and the inability to listen to what they are saying on the part of the government.
"Teachers are just now completely fed up of the government saying 'we won't talk to you unless'. That is not the job of a responsible government."
Labour leader Sir Keir Starmer urged teaching unions and the government to get around the negotiating table following reports that teachers have voted to reject the latest pay offer.
Sir Keir told LBC: "I am disappointed because I want to see this resolved. Obviously it is back around the negotiating table now but I would urge both sides to compromise and to come to an agreement as quickly as possible."
The Labour leader added: "Obviously I support their right to take industrial action, it is very important I say that.
"But I will be clear, I don't want to see industrial action and that is why I want the Government around the table resolving this. It is possible to resolve these disputes, and the sooner the Government gets on with that the better."
Meanwhile, teachers in Wales have ended their strike action after voting to accept a pay offer comprising an additional 3 per cent pay award for 2022/23 alongside a 1.5 per cent one-off payment, and a government-funded 5 per cent rise for the following year.
Scotland's largest teaching union has also accepted a pay deal to end long-running strikes, which it said would amount to a 14.6 per cent increase in pay for most teachers by January 2024.