Years back there was a BBC computer program that let students watch molecules jiggle on the screen as they changed the temperature and pressure. It was heaped with praise, but when the last BBC computer visits skip city, this fine teaching tool will be no more. Here to fill the vacuum is States of Matter. Old friends of jiggling molecules will find them again - now contained in a cartoon-style multimedia package.

A Scotsman tells pupils that particles have energy, that these are moving in different ways and can be compressed or not. Later, he tells them how solids can melt and how liquids boil or evaporate. It is the stuff of school science, rather than home science, and it is easily warmed to.

As pupils hear how the water disappears from wet clothes, they’ll see how some water particles have enough energy to break free. Even better, many of the lessons, each lasting a few minutes, have an activity where they heat things to find their melting-point or sort moving molecules into solids or liquids. All this is well animated, although I have a few quibbles about accuracy.

There is much to like: in a revision exercise, they match on-screen changes like liquid-to-solid to “ing” words such as sublimating, six smart printable handouts summarise the key points, which, if printed “without text”, are handy for note-taking or homework.

Unlike most CD-Roms you could use it straight out of the box. Use it in class to illustrate a point, or place it in the library.

Because the text is spoken, rather than “read at your own speed”, some will find the pace perfect, others will want to hit fast forward. Some will not like the professor character, others will wonder if he is trying to correct a shortage of men in science.

The quality of States of Matter outclasses much else for this age group. Interestingly, it comes from the producers of The Chemistry Set, which is the only other useful chemistry title focused on school. For tackling an area as needy as this and for doing it so well that it bubbles, we ought to give the makers a knighthood.

* Moving Molecules for the BBC computer was originally published by Cambridge University Press