A head teacher praised by David Cameron in June for not closing her school during industrial action says she will strike for the first time in her life.
The coalition government says the public sector pension bill is unsustainable and reform is needed.
Sue Foster-Agg, of The Vaynor First School, Redditch, said initially she thought a fair pension deal could be reached, but no progress had been made.
An estimated two million public sector staff are due to strike on Wednesday.
The government has proposed a 50% increase in pensions contributions, from 6.4% to 9.6% of an employee's salary. It also wants to raise the retirement age to 68.
Mrs Foster-Agg, a head teacher of 11 years and a loyal Conservative supporter, said: "This has been the most difficult decision of my professional life.
'Pensions not bust'
"It's a very difficult decision for every teacher.
"Putting the children first is uppermost in our minds and it is not a decision we take lightly.
"This action for me is really in support of all the younger teachers who are going to lose out," the Worcestershire head teacher said.
"My concern is that they are not going to attract the best people into the teaching profession and you are not going to get the number of heads coming through, when there is already a shortage of head teachers.
"Our pensions are not bust. Two recent audits have shown that the pension pot is viable for another 50 years and we are not going to be a burden on the taxpayer.
"The difference in the summer was that I had faith in the government that they could work out a solution.
"I have not seen any progress so I have decided to follow my union's advice to strike."
The 55-year-old from Redditch said her decision was also partly based on the higher number of teachers involved in the strike this time around, which made it unfeasible for the school to open.
The Vaynor First School, which educates children aged up to 13, was praised by Mr Cameron in the House of Commons in June ahead of strikes that saw about a third of schools close.
At the time he said: "I would congratulate them for doing the right thing and for keeping their school open."
Roger Seifert, professor of industrial relations and human resources management at the University of Wolverhampton, estimated that about 90% of all schools and colleges in England would be closed on Wednesday due to industrial action.
He said: "Not only have you got the biggest number of workers involved in a one-day strike for about 40 years but it is especially significant for who they are.
'Not mindless militants'
"You've got a high proportion of women as the teaching union is highly feminised and a high proportion of white-collar workers too, including the First Division Association whose members are drawn from senior civil and public servants."
He said previously strikes on this scale were dominated by male, blue-collar workers, such as the miners in the 1980s.
"This is the first time I can remember in a long time that we have seen the National Association of Head Teachers voting to strike," he added.
Prof Seifert said the strikes would place the Liberal Democrats in particular under pressure because history had shown that about 40% of teachers vote Liberal Democrat.
He said that posed another problem for the government.
"It's difficult for them to rubbish the strikers, because of who they are.
"Teachers, and especially head teachers, are people of some standing in their community. They can hardly brand them 'mindless militants' as part of their anti-strike propaganda," he added.