"Critical friend" - remember that phrase, fashionable in schools about 10 years ago? This was the colleague nominated to be our partner, our source of informal support and advice, whether we liked it or not.
I do not want to hurt too many feelings here; there may be readers out there who still have a close and ongoing relationship with their critical friend. Some might even have fallen in love. There may be children around today who were conceived by critical friends on warm Mediterranean sand dunes at sunset. But in my experience the enforced friendship was never going to last. I cannot even remember who mine was. He or she quietly drifted away, rather like the idea itself. An older initiative in schools called "real friends" seemed to offer a better and longer-lasting service.
No real harm was done by this scheme, but schools surely cannot afford to spend any time on such red herrings today, given the numerous time-consuming changes to exams and courses. Schools, training colleges and research bodies need to be far more discerning in separating worthwhile new teaching ideas from those lacking credibility or substance.
We also need to be sharper in recognising the "new" project with the neat, fresh-sounding name which is actually pedagogical mutton dressed as lamb. The problem historically is that we have all been too nice and open-minded. We have been too slow to dismiss duff or dressed-up initiatives.
That said, it's not always easy to predict which teaching ideas are here to stay and which will prove to be the transient loom bands of education. Where, for instance, will history eventually place - in order of educational import - the following vogueish sample: learning walks, learning walls, learning waltzes (I may have made that one up), stilling, oracy, virtual learning, Assessment for Learning, thinking skills, personalised learning and pupil voice? Which of these will stay with us and which will come to be seen as mere fancy dress?
Sometimes a new idea, however helpful, fails to take off simply because of unhelpful circumstances. Take the sorry story of another recent initiative: independent learning. Making students more responsible for their work sounded like a fine plan, particularly with all the electronic research and communication technologies available today. But it was born just as schools and teachers became more desperate than ever about target grades and pass rates, not just for the sake of league tables but also because of performance-linked pay.
Independent learning began to be seen as too risky for too many pupils - for exam students in particular. Too many might simply fail to rise to the challenge. Instead, many schools now control exam learning more closely than ever before, meaning that many pupils feel less capable of independent study at the age of 16 than they did at 11.
The best new ideas will thrive only in the right context. I hope our new critical friend at the Department for Education is taking that on board.
Stephen Petty is head of humanities at Lord Williams's School in Thame, Oxfordshire