Many kids are now so overweight that they will die before their parents, falling victim to heart disease and diabetes in middle-age. Meanwhile, in Britain's secondary schools, those same children can buy fizzy drinks and crisps without leaving the building. Some 95% of Britain's secondaries have vending machines, which give an average-sized school about £15,000 a year profit. So schools teach children about the importance of a healthy diet in PSHE, then take their cash at break.
Heads are unrepentant. If schools didn't sell the stuff, the kids would just go down to the local shop and get their sugar fix there. This offers some interesting possibilities. Schools with a drug problem could invite the dealers in, take a rake-off, and invest the money in a "just say no" programme. Fights in the playground could be dealt with by rearranging the bout in the school gym at 4pm. Or heads could decide that some children have no chance of a decent grade at GCSE and assign their worst teachers to those groups. (Whoops, reality crept in there - hundreds of schools already do that.)
As a teacher I gave up attempting to justify the hypocrisy which schools specialise in: the end of term assembly where 1,200 kids sat in their stockinged feet because shoes would "damage the hall floor", while 70 teachers filed into the hall in heels; or the classic, "You will all stay in after school unless someone owns up", even though collective punishment is outlawed under the Geneva convention.
History lessons are dominated by Stalin and Hitler, and how they trampled over basic human rights. Then, in (compulsory) citizenship, pupils are encouraged to debate issues, develop an understanding of the political process and vote for a school council. Then they are marched down to the hall to be told that the toilets will be closed at lunchtimes because of smoking or some other crime that the majority of the pupils had nothing to do with. The kids can contemplate the human rights issues implicit in this policy as they wait with their legs crossed in the dinner queue - which is bypassed by the teachers, who walk straight to the front.
Global warming is one of the most important problems the coming generation will face. And yet most schools are temples to waste. Lessons on sustainability take place in uninsulated classrooms using worksheets that have been printed on unrecycled, chlorine-rich paper. The busiest machine in school is the photocopier.
The hypocrisy is found at every level, and it starts at the top, in government. Twenty years of reform has produced a conveyer-belt approach to learning. Knowledge arrives in unrelated, bite-sized chunks. What does it all mean? Who cares as long as it can be assessed? Don't think about the problem. Write it down. There's a test next week.
· Phil Revell is an education journalist who taught in secondary schools for 18 years.