If, by some divine dispensation, we could come back and look at schools 100 years from now, what would strike us most? Ask most people and they speed off down technological highways - hand-held computers, individualised learning programmes. But I believe the most profound shift will have been towards the recognition that mind and body are as one, and that only by attending to the latter can the former properly be taught.
The teachers of the next millennium will, I'm sure, laugh themselves silly about the dark old days when schools struggled to tackle learning standards without looking to children's diet and exercise. It will seem as archaic as running cars on lead-laden petrol or dumping half-treated sewage in the sea. They will chortle over ancient school-dinner menus and split their sides over the timetables which corralled PE into a couple of squares a week.
Do you know, they'll say to each other, they used to expect kids just to amble in off the street, throw their crisp packets in the bin, sit down and start working!
These are the kind of thoughts that wander through your mind when forced to wait in a hospital casualty department for a child's arm to be strapped up - sudden accidents being perfect for focusing the attention on the link between mind and matter.
This particular child had tripped while roller-blading and, since more than half the upper-limb fractures in this country are now caused by in-line skating, it was hardly an unusual accident. But I've come to know that few accidents are quite what they seem. Why does a child who has roller-bladed for years fall that one day and fracture her wrist?
Unpick the events and you find not only physical circumstances - borrowed skates and no wrist guards - but mental ones, too: tension and excitement from being in a new situation; anxiety over forgotten money for a school trip.
In fact, we're all perfectly familiar with the link between mind and body. Cooks know that cakes baked in a bad temper won't rise. Tennis players see their game plummet after early mistakes.
Ditto the effect of body on mind. Deprive the mind of what it needs by way of food, water and oxygen, or give it too much of what it doesn't need by way of fat, salt, sugar and carbon dioxide, and it quickly grows silted up and stale.
Our child with the fractured wrist, who now finds herself unable to swim or cycle, is subsiding likea cooling souffle. She mooches around the house eating biscuits, disinclined to do anything constructive.
These days we know so much about how we work, and are learning more all the time. We know that we need whole grains, fruit and vegetables, and that we need to raise our heart beat three times a week to 150 beats a minute for 20 minutes in order to keep obesity and heart disease at bay.
We know that concentration slumps after 40 minutes, but that moving around can restore it; that bursts of high-energy exercise dramatically lift depression; that positive thinking can affect physical prowess; and that removing food additives modifies the behaviour of aggressive teenagers.
But almost none of this translates into how we bring up children. The modern child is pushing out new boundaries in junk-food eating and television watching, yet we kid ourselves that by inserting one helping of broccoli in among the oven chips and ice-cream we are providing a balanced diet, and that children don't need structured exercise because they are always "on the go".
The facts tell a different story. One recent study of children's physical fitness, by researchers at John Moores University in Liverpool, which tracked 80 nine to12-year-olds over three years, found children's heart rates barely differed from asleep to awake and none achieved the three-times-a-week fitness level needed to stay healthy in later life.
The last national survey of school children's eating, published eight years ago, showed that more than three-quarters of all children ate too much fat, and that older children (especially girls) who favoured fast-food outlets, had a diet deficient in iron and all manner of other vital nutrients.
So much of what we do when it comes to child health seems an evasion of the real issues. Why try to wean children towards a healthy diet with ever more processed food? Or entice them into sport with gimmicky programmes of sword-dancing or ocean-racing? Or waste time lamenting unstimulating school playgrounds when many a lovingly painted hopscotch grid is wandered across unseen by girls deep in discussion of last night's Neighbours?
The Labour Government has said it will reintroduce national nutritional standards for school meals, but why stop there? If we're going to go back to basics, then let's really do so, and put a third national target up beside literacy and numeracy. Let's call it personal education and throw in the fundamentals of diet, exercise, and maybe even emotional self-management, too.
This new subject would need no new resources, and have no staff training implications. It would be so simple idiots could teach it, and so vital, that only idiots wouldn't.
Schools would be obliged to get their students moving - five minutes' running on the spot after school assembly, aerobic videos at lunchtime; stretch and breathe breaks between lessons; brisk walks for teenagers who loathe games. Heart rates would be measured and attainment targets set.
School meals would be uncompromisingly healthy. No question. Out would go chips, in would come carrot sticks. All unhealthy snacks would be banned, ice-cream vans would not be allowed to park within a mile of school premises, and parents would have to sign contracts with the school to provide brain-healthy food.
Children would sit in rows and be instructed (whole class teaching, no discussion) in how to care for themselves. They would be told, with illustration, what will happen to them if they don't.
Beyond school, sweets would be taxed like tobacco, television advertisements would hammer home the message of child health, and compulsory parenting courses in health and nutrition arranged in every cadre. Sorry, area.
Of course, however, by the next millennium such measures could come to be as outdated as quill pens.
Do you know, tomorrow's teachers will say, handing out brain pills and plugging in the electronic class exerciser, back in the old days they actually tried to make kids healthy by running and eating cabbage. Can you imagine? And they'll split their muscle-toned sides laughing.