We all know the pleasure a teacher gets when a pupil grasps the implications of what he or she is saying and asks the pertinent question while the other 29 are gazing blankly at the walls.

For example, at key stages 3 and 4, non-renewable energy sources are discussed, including the possibility that the oil which powers the western economies could run dry in as little as 40 years. At which point, one day, one of my pupils asked, “What happens then, Sir?” What a question! Within the lifetime of this child, she may see a change in society of greater magnitude than ever my generation saw. When I was her age, we used slide rules and logarithms - and I’m not that old.

It is a question of consuming interest for it is not just the internal combustion engine that will need to find a cheap and easy alternative fuel. Imagine the acres of land that would be needed to grow crops for oil or to ferment into alcohol to replace petrol. And aircraft fuel can only be made from crude oil.

And it’s not just an energy question. Oil is used as a feedstock for a range of materials - paints, dyes, drugs, plastics, glues, cosmetics, detergents, synthetic rubber and fibre, to name but a few. Alternatives will be found for many, but at what cost?

Estimates of oil reserves stretch as much as 80 years’ worth. It is the most astounding indictment of our complacency that we think that this is far enough in the future for it not to matter, much. And yet the war in Kuwait is an indication of our insecurity, and a foretaste of what might happen.

Until now proven reserves have kept pace with consumption. But how long will it be before the finding of oil fails to match its usage? Twenty years? Ten? At that point the rise in oil prices will make the shuttle look stationary. And the ensuing recession will make the Wall Street crash a mere fender-bender.

Am I being too alarmist? Let me point you to the millennium bug. We had 30 years to sort that out but it was only three years before December 31, 2000 that the alarm was raised.

So, Lindsay, Tom, Matthew, and everyone else in Year 9, the best answer I can give is: either become a chemist and specialise in oil alternatives or, set up a line of sailing ships. Come to think of it, it would be nice to see the tea clippers make a come-back. All right, container clippers, then.

Merlin J Southwell is a science teacher in Aylsham, Norfolk.