More than 11,000 schools in England have been hit by Thursday's walkout by teachers, according to Government figures.
In total, 5,679 local authority run schools were shut, and another 4,999 were partially closed, according to data gathered by the Department for Education (DfE). A further 201 academies and city technology colleges were also closed, with 235 partially open. It means that overall, 11,114 were hit by the action.
The DfE said 4,320 local authority schools had not reported their situation, while 5,860 were fully open. It means that around 27% of schools were closed, 24% were partially open, and 28% were open.
In a written ministerial statement laid in the Commons, Education Secretary Michael Gove said: "I know that many teachers are concerned about the changes that have been proposed to their pensions. But I believe that we must resolve these differences through negotiation and that the action today, while negotiations are still going on, was disappointing and unnecessary."
He said he was "grateful" to heads, governors and teachers who had gone into work, adding: "I am also disappointed that there has been disruption to the lives of so many parents across the country."
Hundreds of thousands of teachers, lecturers, civil servants and other public sector workers are staging a 24-hour strike in protest at the Government's plans to increase their pension contributions and raise the retirement age. The action has forced the closure of courts and offices and disrupted Government services and travel.
Members of the National Union of Teachers, Association of Teachers and Lecturers, University and College Union and the PCS are taking action. PCS general secretary Mark Serwotka, said: "This is the best-supported strike we've ever had."
The Prime Minister's official spokesman described the strike as "unnecessary and premature", adding: "There is this debate that is raging about unaffordable versus untenable. The fact of the matter is this was looked into very thoroughly by Hutton and he concluded that we needed to reform public sector pensions."
Labour leader Ed Miliband said: "These strikes are wrong at a time when negotiations are still going on but parents and the public have been let down by both sides because the Government has acted in a reckless and provocative manner. "
TUC general secretary Brendan Barber accused the Government of unfairly "hammering" millions of low and medium-paid public sector workers by piling the burden of reducing the country's debts on to them. But he also criticised Labour for a lack of support in not speaking up strongly enough in defence of the current pension plans agreed when they were in government.