It is seen as an essential classroom technique, taught in teacher training colleges and inspected by Ofsted. But despite the seeming ubiquity of Assessment for Learning (AfL), the strategy is largely missing from England's schools, according to the two academics who popularised it.
It is a situation that Dylan Wiliam, emeritus professor at the University of London's Institute of Education, views as a "tragedy" - one he blames on the interference of government and on himself.
Fourteen years have passed since Professor Wiliam co-authored Inside the Black Box, the booklet that introduced a generation of teachers to the concept of using assessment to help pupils improve, rather than to grade their knowledge (see panel, right). Tens of thousands of copies have been sold and most teachers and schools are familiar with the term. But the problem, says Professor Wiliam, is that they have not understood it properly.
In his first comments to the media on the failure of the technique to take hold in schools, Professor Wiliam has laid much of the blame at the door of the Labour government for launching its own #163;150 million AfL scheme in 2008. And he believes the impact is still being felt in schools today.
"There are very few schools where all the principles of AfL, as I understand them, are being implemented effectively," Professor Wiliam told TES. "The problem is that government told schools that it was all about monitoring pupils' progress; it wasn't about pupils becoming owners of their own learning.
"We have (DfE officials) saying: 'We tried AfL and it didn't work.' But that's because (they) didn't try the AfL that does work."
Professor Wiliam's comments follow a similar admission from his Inside the Black Box co-author. In 2010, Professor Paul Black from King's College London said that the technique was not being used in a "very large number of classrooms", also blaming government for emphasising the measurement of pupil progress.
Professor Wiliam said that he and Professor Black were consulted on the government's AfL strategy and pointed out faults, such as its failure to mention the dangers of grading, but to no avail, as "they failed to include some of the most basic ideas that we had been advocating".
John Bangs, honorary visiting fellow at the University of Cambridge, described Professor Wiliam's work on AfL as "authoritative and innovative". But he said that the technique had not had the impact it should have done because of the lack of a proper strategy for teacher professional development.
"Instead we had a highly bureaucratised and ossified way of turning AfL into some kind of weird amalgam of formative and summative assessment where everything had to be recorded to the nth degree," Professor Bangs said.
Professor Wiliam partly blames himself for underplaying a "really crucial aspect" of AfL: "designing your teaching on the assumption that pupils aren't going to get it all the time".
"The big mistake that Paul Black and I made was calling this stuff 'assessment'," he said. "Because when you use the word assessment, people think about tests and exams. For me, AfL is all about better teaching."
How it should be
Dylan Wiliam's key Assessment for Learning strategies:
Clarifying, sharing and understanding learning intentions.
Eliciting evidence of pupil learning, through the use of tests and quizzes, for example.
Providing feedback that moves learning forward.
Using pupils as learning resources for one another, through methods such as peer assessment and peer tutoring.
Encouraging pupils to be owners of their own learning, through self-assessment and other methods.