The 1952 movie Scaramouche has the longest fencing sequence ever filmed - six-and-a-half minutes of Stewart Granger and Mel Ferrer leaping up and down stairs, swinging from chandeliers and eyeballing each other menacingly across interlocked swords.

What does this have to do with teaching children to use rulers? Well, I reckon that in the weeks after Scaramouche was showing at the Alhambra, Barnsley, the school I attended got through more wooden rulers than ever before or since.

Rulers were what my generation practised fencing with. In fact I was almost tempted to rate this collection according to some sort of thrust, lunge and parry index. Of course, rulers could be other things too - improvised catapults, tools for goosing people or ripping open their fly buttons, corporal punishment implements in the hands of infant teachers.

Even at the legitimate end of the spectrum, a ruler is a multi-purpose tool. It measures short distances, acts as a straight edge for drawing lines and is a ready-made number line for helping young children to do simple “counting on” calculations.

Conventionally, each child has a ruler, which is used for everything. Another approach is to have a range of different rulers available in the room, so that children can choose whichever is appropriate. This lines up well with the current drive for children to take more responsibility for organising themselves.

A half-way technique, used by some primary teachers, is to let each child have a ruler for everyday use, but to keep back a class set, always in pristine condition, to be given out and used only in maths lessons.

Some features of the standard classroom ruler owe a lot to tradition. In the 1950s, a ruler was expected to last a long time. You were given your ruler when you entered school, and you had to keep using it, despite rough edges, ink stains and chewed ends. You also had to use it to draw straight lines with a steel-nibbed ink pen.

Thus, when you look at, say, NES Arnold’s familiar varnished wood Bevelled 30cm Ruler (Pounds 4.35 pack of 10) you find that it has a spare bit at each end to account for wear, and is bevelled so you can turn it over and use it with a pen. Neither feature is all that relevant these days. Rulers are so cheap that it makes little sense to keep them in use when they have become unpleasant to handle, and the “chewing area” has the disadvantage of preventing children from starting to measure at the very end of the ruler.

Measuring millimetres with a classroom ruler, it seems to me, is always going to be fraught with difficulty. When you teach children to measure - placing the ruler accurately, controlling it with one hand and handling a pencil with the other - you need to keep things simple. Perhaps more in line with the needs of younger children is the 30cm Junior Ruler (Pounds 5.25 pack of 10) printed in centimetres only on one side. The centimetre divisions are very clear and go all the way across the ruler. This one, incidentally, although also of wood, has “dead ends” - that is, you can measure right from the end. It is flat, not bevelled - and this arguably makes it a little easier for young fingers to hold it down on the surface being measured.

Another wooden dead-end ruler is the 39cm General Purpose Ruler (Pounds 4.95 pack of 10) which is double sided - millimetres on one side and centimetres and half-centimetres on the other. This seems a reasonable compromise, and the price is attractive for a wooden two-sided ruler.

The ruler that is probably most common in schools is NES Arnold’s plastic Non-Shatter 30cm Ruler (Pounds 3.25 pack of 10). It is a sturdy product at a reasonable price. Bevelled on the edges, it has a recessed channel along the centre that helps control with the fingers. It does not have dead ends, but it does have centimetres and millimetres on one side and centimetres and half-centimetres on the other. A class pack of these rulers in different colours is even more economical at Pounds 23.95 for 100.

It is also available in clear plastic - a useful aid to teaching measurement on the overhead projector. To my mind this ruler represents better value than the equivalent double-sided plastic Helix product (in the NES Arnold catalogue at Pounds 2.75 for 10).

Metre rules are a bit too long for swordplay - at least until you grow up and become a head teacher or an OFSTED inspector. The simplest one here is the First Metre Rod (Pounds 3.30 each) which has no printing on it, but is divided by colour into 10-centimetre sections. The simplicity is supposed to reduce confusion for very young children.

My feeling, though, is that the Primary Metre Rule (Pounds 3.90) which uses marks for each centimetre, and numbers for each five centimetres, is more versatile. One problem, however, is that the printed number “100”, which actually denotes the end of the ruler, looks as if it labels the mark immediately above it, which is really 99cm.

Carrying a little more detail, but still quite basic, the Plain Metre Stick (Pounds 2.60 each) has centimetres marked along one edge, and half-centimetres on the other.

All of these metre rules are made of wood. The Chunky Metre Stick (Pounds 5.99 each) is plastic. It is, in essence, a hollow plastic tube of rectangular section and thus is very sturdy and stiff. It is marked in centimetres on one edge, with alternative colours every 10cm along the other edge.

Many teachers like younger children to encounter the concept of measurement without having to cope with the language of numbers and standard units. For them, the NES Arnold catalogue has several rulers and tape measures which are marked off in arbitrary divisions illustrated by pictures. Thus a child may measure a book at “five crocodiles long” (or three teddies, or seven elephants). Tapes are, of course, useful for measuring around things - your friend’s head, a tin can. Picture Tape Measures are Pounds 9.25 for five and Picture Rulers Pounds 9.95 for five. An Arbitrary Measuring Kit including several measuring tools and some teachers’ notes costs Pounds 36.95.

Every one of these rulers and tapes could - and should - be used as number lines for counting exercises as well as for measuring. But the Picture Ruler is particularly good for this because it is cleverly colour-coded and the pictures are grouped to make it easy to count in twos and in fives.

Best buys? For standard issue in both junior and secondary schools I like the Non-Shatter Ruler, in its transparent version. At lower junior and key stage 1 levels, I like the 30cm Junior Ruler. As a multi-purpose counting tool, the Picture Ruler is good for younger children.

All these products were supplied by NES Arnold, Tel: 0115 971 7700. The catalogue prices may be subject to various discounts, and the same or similar products may be available at different prices from other suppliers.