Terrorism? Must be the teachers' fault for alienating Muslim children.
Teenage pregnancies? Obviously the result of too much (or too little?) sex education. Yet children spend little time in school and do not listen much to teachers when they are there. Television, films, pop music, computer games, comics, books and advertising, partly mediated through peer groups, have a greater influence on youthful behaviour than any teacher does.
One wonders why this is not more widely recognised. The explanation lies in how national debate is framed. Schools, being part of the public sector, can be regulated; but the big influences on young people are almost all in the private sector. Politicians, however, won't regulate the latter. This is not because they are socially libertarian but because nothing can stand in the way of profit. Indeed, it is precisely because our rulers are so reluctant to regulate economic behaviour that they aspire increasingly to regulate social behaviour.
As the American writer Thomas Frank points out in a newly-published book, left-wing parties in the West have more or less taken economics off the agenda. They will not discuss the distribution of wealth. Here, the pay of company directors climbed 12.8 per cent last year, while average earnings rose 4.7 per cent, continuing a long-running trend. Across the Atlantic, the disparities are even more dramatic. But no mainstream party will stir up class hatred on these grounds. Politicians prefer to wage class war in the social and cultural arena, blaming elites in the media and professions for flouting the values of ordinary, respectable folk. The US Republicans have done this brilliantly. The Conservatives here keep trying - through Michael Howard's recent speeches on "political correctness", for example.
New Labour tries to outflank them with its talk of ending "the 1960s consensus".
Teachers may not think they are an elite, but they are in the front line.
Likewise, BBC personnel may think they are poorly-paid and overworked - but, being in the public sector, they can be bullied and frightened. It is true that the tabloid press has done far more to lower moral standards. It is also true that teachers, and other public-sector workers who take occasional days off work, rip the country off to a lesser extent than chief executives who get pound;1million salaries. Teachers don't earn much in the first place, so a bit of skiving is neither here nor there. Indeed, for what most teachers are paid, I'd expect a pretty rotten job. Company directors, on the other hand, cannot possibly deserve the salaries they are getting: poor value for money is built in to their excessive pay.
But the point is that they are in power, and you are not. The former BBC sports presenter David Icke, now a born-again Christian, believes the world is run by extra-terrestrial lizards. I think he is on to something. Whoever is running the world doesn't care much about those - pupils, teachers, parents - in the average state comprehensive. The rulers may as well be lizards. Mr Icke has found an apt metaphor - like those 1950s science-fiction films that echoed cold-war paranoia by having mysterious forces take over people's minds.
So, as the school year starts, my advice to teachers would echo that of those old films: be afraid, be very afraid.
Peter Wilby is editor of the New Statesman