Described as suitable for children of 11 and over. Scales is designed to teach pupils how to read a thermometer, a measuring cylinder, a burette, an ammeter, a stop-watch, a vernier and a micrometer screw gauge. It should provide an essential skill for those taking science and some craft courses.

The program loads easily and gives the user a menu from which to choose the required measuring device. Although the accompanying booklet - there is one for both programs - says that the cursor is moved up and down using the U and D keys, the arrow keys work just as well.

A diagram is drawn for each device and the user is asked to input the reading to the correct level of accuracy. Incorrect or null answer (by pressing RETURN) produce an explanation, and pressing f0 gives the current score and the chance to change device.

The vernier and micrometer gauge displays are paticularly helpful. The measuring cylinder, however, is hard to read on a monochrome monitor and this certainly demands a different physical skill from that needed to read the real thing. The notes make the point that pupils should have seen the real device in use and should be aware that, although the program does not demand units every real application will.

The program is intended for both class display or individual use. For general class use the numbers seem rather small, but the layout, mode of operation and helpful corrections make it ideal for small group use. The program will be a boon to teachers who have found progress of practical work slowed down by pupils who cannot read a scale and who need individual attention.

Transverse Waves is for pupils following Physics courses at O level or above. The program covers interference, reflection and beats, all of which can be displayed with a varying number of points, varying speed and the ability to freeze a frame by pressing the spacebar. It is an excellent program that gives endless possibilities for pupils of average and above-average ability.

These programs are robust, the screen displays are clear and uncluttered and they both meet worthwhile educational objectives in an appropriate way. My only criticism is that the brief booklets don't give the average teacher sufficient help to get the best from the programs. A few helpful sample runs showing some of the advantages of using the computer would have been helpful, particularly in the Waves program.

Neither booklet gives much educational philosophy and the user has to learn a lot by trial and error. For example, it would be useful to know how Scales responds to errors. Does it immediately repeat a question thinly disguised or wait a few turns before repeating it - or ignore the error altogether?

The programs incorporate the Five Ways Software security systems to prevent copying or listing.