It’s the ultimate sheet of squared paper. The rows and columns of “squares” - or cells, as they are called - can be easily adjusted to any size. So it’s ideal for creating any document that involves elaborate tabulation: mark books, timetables and those endless lists which teachers seem to find indispensable. Unlike a paper-based list you can make amendments without messing up the overall appearance. You can change the type face, add flashy headlines and produce a perfect result every time.

But under-exploiting a spreadsheet in this very limited way is like keeping a Porsche parked in the garage so you can occasionally use the ashtray.

A spreadsheet is for doing sums. Highlight a vertical column or horizontal row of figures, or even individual cells picked from anywhere, and the spreadsheet will instantly add them up, and then print the result in any vacant cell you choose. You could have hundreds of sums on screen simultaneously - including a sum that totalled the result of all the other sums. If you then chose to alter any one of the original figures, all the totals are automaticallyre-calculated.

If you tell it, the spreadsheet will also happily subtract, divide, multiply or carry out hundreds of the other abstruse mathematicalfunctions.

It’s the perfect way - the only way - of setting up complex mathematical models, which is why the business and science community find the spreadsheet indispensable. But if you are a beginner, you won’t ask it to do much more than take charge of your mark book.

It can, of course, give you running totals for each pupil. You could also add together the boys’ scores, and the girls’ scores; subtract one from the other; express the result as a percentage and play with the figures in any way that takes your fancy - without ever having to do the tedious arithmetic involved.

The spreadsheet is just as useful for the busy head of department. She types in her resource requirements for the year, and finds that it will entail serious over-spending. She can now delete items, or reduce quantities; she can alter any figure, any number of times, and always have an accurate running total. She might try thousands of subtle alterations that she couldn’t have contemplated if she had to do all the calculations herself.

Pupils, too, can benefit enormously from this freedom. They can experiment with numbers and mathematical concepts without being bogged down in the endless working out which usually makes this kind of exercise such a chore. And there is no reason why the spreadsheet should be confined to science or maths. The educational software houses offer ready-made data covering a range of topics spanning the whole curriculum. So, for instance, they can study the day-to-day accounts of an impecunious Victorian household. By altering the numbers, they can pose and answer any number of hypothetical questions that they can think to ask. What would happen to living standards if the price of bread fell? If the mother lost her wage? If father spent less in the alehouse?

The spreadsheet has a further facility which makes it a marvellous classroom aid. It takes only a few clicks of the mouse to convert those potentially intimidating rows and columns of figures into eye-catching graphs and charts. Not only do these bring statistical information vividly to life, but also make the sort of impressive wall display which has parents gasping “we never had things like that when we were in school.”

Pupils can also use the spreadsheet to log data from experiments and surveys, or simply to make their own lesson timetable and homework lists. But if they want to horde vast quantities of information - and what child doesn’t? - they really need a database.