Lesson one is never to overlook the fact that educational standards improve because of teachers, not despite them. Lesson two is that bolted-on structural or systemic reforms, however theoretically powerful and consistent, do not in practice achieve either cultural change or practical improvement.
The current dilemma for the Conservatives is an overdue consciousness of those lessons - hence Education Secretary Gillian Shephard's call for five years' stability promises either a period of positive consolidation, or (just as possible) half a decade's rigor mortis if her government's reforms turn out to have been still-born.
The parallel dilemma for Labour - widely seen as the next Government in waiting - is what to do if elected. Do they go for a minimalist strategy of little or no change, thus embedding policies which, out of government, they consistently opposed? Or do they opt for a change agenda, and risk alienating further teachers already punch-drunk with reform?
Let us take a mere example - city technology colleges. In a radical and contentious experiment, the Conservatives sought to tackle several issues simultaneously. First was the attempt to change a deeply ingrained, characteristically British and economically suicidal prejudice against technological, vocationally-focused education and training, an issue flunked by every administration since the Second World War. A second motive was to put industry - carping ever since the Seventies about educational standards - on the spot by challenging the private sector to put its money where its mouth was. The message was: stop whingeing from the sidelines, get involved and get your cheque-books out. The third imperative was the laudable goal of creating better opportunities for children in the inner cities, for whom an unrelievedly academic education was too often a turn-off and a stimulus for dropping out.
However popular the 15 CTCs may be in their own localities, as a national experiment the initiative has been an expensive flop. The reasons are simple. With the exception of a handful of philanthropic corporations or individuals, the experiment has been cold-shouldered by big business. More important, the colleges have not been the promised "beacons of excellence". It was never possible that they would be, for government by metaphor cannot work.
Excellence is not a form of benign measles, to be caught if you are close enough to a source of infection. Taking CTCs out of a local network or infrastructure had to mean that they could never, however good, serve as an enhancing role model for other institutions - particularly if those institutions were more inclined to resent the investment made in them than look to them as exemplars.
So what should the present Government do, given that admitting failure, however heroic, or only limited success is not a marked character trait of any politician? Option one is quietly to accept that the initiative has not worked. Option two is to rewind the tape and dismantle it. Option three is to try to turn the failure into success, and that is what the Government is attempting by extending the opportunity to opt in to the reform to all publicly-funded schools.
What would an incoming Labour government do? Shutting 15 well-equipped schools would not make sense. But what would returning them to LEA control mean? Particularly since some of them were not local authority schools in the first place. And particularly since "local authority control" has become an increasingly empty phrase.
A different systemic answer is no more likely to solve the fundamental problem than the answer it replaces. Whether we are talking about LMS, grant-maintained schools, CTCs, the national curriculum and testing, or examination league tables, inexorably we return to key questions for any government. The first is, what are the positive levers for school improvement? How do we create a climate in which teachers see school improvement as an internal desirable imperative rather than an external and threatening demand? The second is, how can improvement he generated in schools which lack the resources, appetite or dynamic to meet the challenge?
It is time for politicians of all persuasions to accept that a hands-off approach is more likely to succeed than throttling legislation and stultifying accountability requirements. It is equally time for a widespread and open professional debate among teachers themselves, open in that it takes full account of perfectly legitimate public concern and interest over the outcome.
Peter Smith is general secretary of the Association of Teachers and Lecturers.