Ofsted has scrapped its “satisfactory" judgement and replaced it with the term “requires improvement".
The inspectorate has said that the change is to target “coasting" schools which have remained “stubbornly satisfactory" for a number of inspections in a row.
However, headteachers have attacked Ofsted for announcing the changes without consultation and within two weeks of the introduction of a new inspection framework.
Under the new approach, no school will be allowed to remain in the “requires improvement" category for more than three years. Schools in this category will also be subject to earlier re-inspections – within 12 to 18 months instead of up to three years at the moment. Schools failing to demonstrate improvements will then require special measures.
The announcement was made ahead of chief inspector Sir Michael Wilshaw attending a “summit" on coasting schools at Downing Street on Tuesday (January 17).
Sir Michael said: “There are too many coasting schools not providing an acceptable standard of education. Of particular concern are the 3,000 schools educating a million children that have been 'satisfactory' two inspections in a row. This is not good enough. That is why I am determined to look again at the judgements we award, not only so we are accurately reporting what we see, but so that those schools that most need help are identified and can properly begin the process of improvement.
“I make no apology for making even greater demands of an education system which has to respond with greater urgency to increasingly difficult and competitive economic circumstances. We will consult properly about the changes that we make but I am clear about our mission."
It is the second sweeping change made by the inspectorate in the past few days following last week's announcement that all inspections from September this year will be conducted without any notice.
However, general secretary of the Association of School and College Leaders, Brian Lightman, warned Ofsted that if any school is given the new “requires improvement" judgement then they must be given the necessary support.
He continued: “Our main concern is about the implementation of these changes. This is the second set of changes to inspection that Ofsted has announced without consultation within the first two weeks of a new inspection framework and a new chief inspector. We have also been told that there will be a further consultation on the future of Ofsted inspections.
“School leaders need to be able to focus on the quality of provision in their institutions but instead they are being distracted by having to look over their shoulders every day to see what the next announcement is."
Meanwhile, Christine Blower, general secretary of the National Union of Teachers, slammed Ofsted for continually insulting schools and students.?
She added: “First we had 'underperforming' schools, now we have 'coasting' schools. Labelling schools in this way is derogatory and insulting to pupils, teachers, school leaders and governors.
“The government's real agenda behind this change is of course inventing yet another category of schools that it will then seek to force into academy status."