From class projects to school notices, any work - especially on the computer - begs for a picture. For folk who cannot draw well enough, and that is a lot of folk, come discs with ready-made drawings, known as clip art, all ready for the clicking. There is no need to pester the school artist, or settle for mere text any more - just point your mouse at these pretty, excellent titles instead.

But here’s a maths, or it could be an art, problem: if a picture is worth a thousand words, how many pictures do you need before you have one for every occasion? The publishers are divided on this one. Bitfolio’s offering of 10,000 images looks massive beside Sherston’s collection of 2,500. And if only numbers count, IMSI’s offering of 101,000 images is nothing short of a blockbuster.

Each of these packages covers the same basic ground. All have pictures of animals, people, food, flags and maps of seemingly every country. Sherston’s also includes a unique set of pictures of Greeks, Romans, Egyptians and other history topics. For science, it has levers, planets and the body. Then there are illustrations of toys, sports, children, Christmas and musical instruments, as well as hundreds of transport pictures. All this smacks of something designed for primary schools.

Bitfolio’s collection is much broader. There are hundreds of decorative borders, ornate letters, signs, shapes and symbols. Then there are cartoons of people working, doing sports and gesticulating - as cartoons do. Everyday objects such as furniture, technology and transport are here too. The result is a collection for which secondary schools and offices will find uses, although it is bitty.

For example, if you wanted to make a zoo scene, you’d have trouble finding enough animals drawn in the same style - some are silhouettes, some are in thin pen, some sketch pen and so on.

The saving grace is that all the discs use “vector” art - so you can enlarge them without losing quality. If you want to change a colour, or wipe the smile off a person’s face, there’s probably a drawing program on your PC that can do it - and easily.

It is worth developing this skill for the SSERC collection, because this is a science teacher’s dream. It is spot-on for assembling apparatus for an experiment worksheet. With several thousand pictures of glassware, lenses, molecules, body organs and minibeasts, this really is the business. Acorn and Mac people will do better than PC types, who need a PC version of Draw to make use of it. In that sense, it is half good IMSI’s collection is something to love and hate. It has so much: 33,000 editable images on one disc, and 68,000 photographs and “bitmaps” on the other eight discs. Three thick books of thumbnail images make a value-for-money package - but I’d recommend some sedatives before taking it on.

It also has some good “Web art” symbols to spice up Internet pages, 2, 000 fonts or lettering styles and a good number of the same pictures in the Bitfolio collection. Image quality is not compromised, but a serious weakness is trying to find a picture of a needle in a huge haystack of CD-Roms.

Which leads to the big issue - finding the stuff you have bought. Like IMSI, Bitfolio has a catalogue of thumbnail pictures, which is very handy if someone doesn’t borrow it. Sherston bundles some simple software to view its pictures and, thoughtfully, each clip is described.

It also has the decency to name a picture of say, the Chinese flag as “China”, instead of “flag 188”. Finally, IMSI and the SSERC disc each have a keyword-search program: the SSERC one works fine, whereas IMSI’s put me back on the tranquillisers.

All this means some might have to pester a school IT expert to find out about “importing” files and searching “folders”. But with a good printer and a great end-product to aspire to, choosing and using clip art is a skill and a real treat.

* SSERC Graphics Libraries for science and technology. CD-Rom for Acorn (Draw format) Pounds 50, Mac (EPS format) Pounds 80. Floppy discs for PC at Pounds 14 each require Oak Draw for Windows at Pounds 66 * Scottish Schools Equipment Research Centre (SSERC), St Mary’s Building, 23 Holyrood Road, Edinburgh EH8 8AE. Tel: 0131 558 8180. Fax: 0131 558 8191 * Sherston Clip Art CD CollectionDual format CD-Rom for Acorn (Draw format), or PC (CGM format) Pounds 49.95 from Sherston Software, Angel House, Sherston Malmesbury, Wiltshire SN16 0LH. Tel: 01666 840433. Web site: www.sherston.com * 101,000 Premium Image Collection CD-Rom for PC (WMF and other formats) and Mac, Pounds 49.95. Available from retail outlets and published by IMSI. Web site: www.imsisoft. com * Bitfolio edition 7 CD-ROM for Acorn (Draw format), PC (CGM and WMF formats) and Mac (EPS format). Price Pounds 38.29 from Longman Logotron 124 Science Park, Milton Road, Cambridge CB4 4ZS Tel: 01223 425558. Web site: www.logo. co.uk