Even the most brilliant marketing teams sometimes get it wrong. There are few stronger and more evocative brand names than that of Harley-Davidson. But when that well-oiled machine tried turning along the less familiar commercial byway of aftershave and general perfumery, the journey was largely met with a cold shrug of leather-clad shoulder from their target customers. There is the escapism of the freeway and there is the grim reality of the bathroom mirror. Never the twain ...

Recent news reminded me of that Harley-Davidson cologne calamity. Education has never conjured up a brand name to rank with the Harley, but a few years ago “formative assessment” came close. It certainly hit the road running. The movement was based at King’s College London, and its challenging report into how children learn spread rapidly across the country. By 2008, we might have expected its principles to be clearly understood and rooted in every classroom. Instead, Ofsted recently reported that its implementation is “no better than satisfactory” in two-thirds of schools.

The ideas of Dylan Wiliam - who spoke so brilliantly and persuasively about formative assessment at our school - and Paul Black rightly challenged many of our traditional teaching methods. No longer, they reported, should teachers put a grade on pupils’ day-to-day work because too often, when they do, the grade becomes the only thing that children remember.

Instead, we should write comments that encourage pupils to think about how they could improve next time. There should be more pupil assessing pupil, more thought about how to ask questions in class, more discussion of pupils’ responses to those questions, more pupil-focused lessons, less teacher-led time.

All these ideas made sense - they still do. It is surely the way to go. The finest teachers I know (in terms of generating both enthusiasm and excellent exam results) are the ones who, along with a natural presence and flair for teaching, follow those principles closely.

Unfortunately, the movement has been undermined for the past few years by one simple but significant marketing blunder. Roughly at the same time as the Royal Mail disastrously re-styled itself “Consignia”, the formative assessment pioneers decided to rename their initiative Assessment for Learning (AfL). It appeared to be part of a ubiquitous obligation to include the L-word in every single education initiative - a phenomenon to which I have referred before.

All right, formative assessment might not have been the sexiest of brand names, but at least it got the essential message across. It asked us to do exactly what it said on the tin. The name AfL, in contrast, was always going to be much more ambiguous. It can be conveniently interpreted in all manner of ways. (“I assess and they learn. What’s so new about that?”)

It isn’t hard to understand why Ofsted was disappointed. Not only can the term AfL become all things to all teachers, but we also wonder whether all Ofsted inspectors are entirely clear and consistent in what they are looking for.

Does AfL even mean what it used to mean? Speaking of the Government’s own so-called AfL strategy, which schools must follow if they want a slice of Pounds 150 million, Paul Black has said: “The main idea conveyed by (the Department for Children, Schools and Families’) strategy is the belief that target-setting and frequent assessment of learning will help pupils learn more effectively. This is not Assessment for Learning. It may help learning, but it is not what I and colleagues have been writing about and helping teachers with since 1998.”

Besides, there is another problem with the Government marketing such a strategy. How can teachers really believe the declared commitment to formative principles when the Government’s own way of assessing schools is so non-formative? It’s as if Jim Knight, the schools minister, had just bought the Harley-Davidson aftershave, but still wished to keep his beard.

How does Jim and Ed Balls’ avowed faith in the original meaning of AfL square with their apparently undying commitment both to inspection-by-grading and league tables? True missionaries would introduce a grade-free system of assessing schools. Inspection would focus instead on detailed, constructive advice and discussion with individual teachers on how to improve their practice. School advisers and inspectors would become one and the same people - their visits one and the same event - thereby making advancement in schools more proactive, faster and cheaper by millions. Exam success - and much else that is good - would follow on from this.

So let’s forget about league tables. For, by driving the whole system with headline-grabbing grades and league tables, you do exactly what grading does to pupils - it distracts, delays progress and sometimes demoralises.

Given these obstacles for AfL, I worry that this vitally important formative assessment movement may one day - like Harley-Davidson perfume - become just another distant fragrance on the great educational freeway.

While losing a brand of cologne does not matter, losing our way in the classroom most certainly does.

Stephen Petty Head of humanities, Lord Williams’s School in Thame, Oxfordshire.