The range of valuable CD-Roms for science teaching and learning has grown so steadily in the past two years, one could almost say that we have now reached a reasonable coverage of the curriculum, especially at secondary level.

Discs such as Electricity and Magnetism, Energy Resources, Forces and Effects, Earth and Universe, and Redshift cover large parts of physical processes. For materials and their properties we have the widely used Chemistry Set and Elements and Materials. Discs like The Ultimate Human Body, British Birds, Facts of Life, Garden Wildlife, and Exploring Plant Science partially cover the area of life and living processes.

For those who want to see all of this for themselves, the National Council for Educational Technology (NCET) and the Assocation for Science Education (ASE) are running a CD-Rom roadshow which will be demonstrating a range of discs for science teaching at teachers’ centres and other venues throughout 1996. If you can’t get to see this, there is a convenient World Wide Web page giving further details.

Curriculum coverage is reasonable if not comprehensive. Use of multimedia in laboratories, classrooms and libraries is increasing though not yet widespread. So now seems a good time to consider precisely the kind of advantages multimedia offers science teachers and a few possibilities for the future.

Why a CD-Rom? What can it do, for example, that a book cannot? This is an issue which many teachers pose and rightly expect a satisfactory answer. A crude and obvious list of what a CD-Rom can provide which a book cannot shows the technical differences between the two: * Audio: a CD-Rom can provide speech and sound effects

* Animation: books can include diagrams but these cannot move, unlike a multimedia package

* Video: many CD-Roms provide short video clips although their quality is (as yet) invariably poor

* Interactivity and tutorial help: books are non-interactive, they cannot provide feedback on a learner’s progress. CD-Roms can be interactive (although not always - see later)

* Alternatives for practical work: a CD-Rom can provide many possibilities for practical or field work which a book cannot. For example: virtual experiments; simulations; real situations to study; surrogate walks and demonstrations.

While recognising these obvious differences, we must also be wary of wild claims often made for multimedia. In particular, we must consider the possible dangers in using multimedia in science.

The first of these concerns portrayals of science: do CD-Roms breed misconceptions? Textbook writers have for a long time been portraying and encapsulating “subject matter” in a textbook format. Authors have been making critical decisions about the text, pictures, diagrams and other representations of their subjects which are to be included in the final product. In a sense they act as “filters” by distil-ling out knowledge in areas such as science and the humanities and re-presenting it in a new package. Teachers also play a key part in this filtering when they use textbooks and other resources.

The same decisions must be taken by the makers and the users of multimedia, but with added importance due to the additional media (sound, animation, video) conferring more charisma and authority on the final representation. Users must take steps to establish multimedia’s credentials. Is it reliable, for example? How powerful are its images? To what extent are the images of multimedia mirrors of reality or distortions of it?

The second danger concerns whether the use of CD-Roms in science teaching is replacing the traditional hands-on experiments and investigations. Several discs allow quite detailed “virtual experiments” to be done successfully and repeatedly on screen, without using up any of the consumables which schools can no longer afford to buy.

The key issue, of course, is whether this devalues scientific activity by removing some of the genuine, hands-on, authentic business of science and placing it in the virtual realm of multimedia.

When discs such as Motion and Forces and Effects contain experiments that are either impossible or unsafe for school labs they more than earn their money. Motion, for instance, focuses on more than 50 video sequences of moving objects which involve forces: cars colliding; golf balls, tennis balls and footballs being struck; spinning objects; gymnasts and weight lifters; rockets and astronauts. The moving sequences can be studied again and again, in slow motion, backwards or forwards, all at once or frame by frame.

Forces and Effects includes its own “Virtual Laboratory” of more than 18 experiments. Some are potentially dangerous and so are best done from the safety of a mouse and keyboard. Others could be done in the lab but the value of having them on disc is that they can be tried and repeated over and over again, changing the variables involved to your heart’s content.

If multimedia use is a complement to good practical work rather than a replacement for it, then its place in science can be justified and it will add value - not take it away. But in order to really live up to their potential, CD-Roms have to become more interactive. Many current CD-Roms are entertaining and attractive but require little or no action from the user other than moving a mouse, listening or reading, watching or pressing a few keys.

Perhaps with the excitement of working with the audio, animation and video clips that characterises multimedia, producers could be excused for neglecting the interactive element. But this interactivity, or just plain activity, has always been a distinguishing feature of good software. It is something we now need to look for, and ask for, from CD-Rom producers.

Programs should allow the user to move things around on the screen; change variables in a simulation; site probes to measure, say, temperature at different points; place marks on the screen and make measurements. In other words, demand some input, thought and activity from the learner.

With multimedia systems entering homes as quickly as schools, we must consider the links between the two. This is given more urgency by the growing number of publishers (such as Dorling Kindersley and Stanley Thornes) now producing CD-Rom titles for both the home and school markets - something which has never really happened before in IT. Teachers will need to manage situations where pupils may know a CD-Rom inside out (such as The Ultimate Human Body) from using it at home. Schools will need a system to ensure that pupils can use school discs at home, and perhaps home discs at school.

In short, teachers may have to relinquish some of their control over children’s learning. The days of the carefully planned, controlled, sequenced and staged curriculum, dished out in timetabled portions could well be numbered. Learning will resemble the buffet more than the set meal.

* CD-ROMS FOR SCIENCE Multimedia Motion and Multimedia Sound 11-18, Pounds 55 each from Cambridge Science Media. Tel:01223 357546

Electricity and Magnetism; Energy Resources; Earth and Universe; Forces and Effects 11-18, all Pounds 99 from BTL. Tel: 01274 841320

Redshift 12 plus, Pounds 49.99 from Maris Multimedia. Tel:0171 488 1566

Garden Wildlife 4 and upwards Pounds 40, and Understanding Energy, 8-14, Pounds 50, from Anglia Multimedia. Tel:01603 615151

Chemistry and Chemistry Set 11 to undergraduate, Pounds 155 from New Media. Tel: 0171 916 9999

Materials 14-16, Pounds 79.99; Elements 14-16, Pounds 79.99; Biology and British Birds 14-16, Pounds 99.99. All from Yorkshire International Thomson Multimedia (YITM). Tel: 0113 243 8283

Facts of Life 12-16, Pounds 95.21 from Projection Visual Communications. Tel: 0171 250 1706

Exploring Plant Science 11-18, Pounds 69 from Attica. Tel: 01865 791346

The Ultimate Human Body 8 and upwards, Pounds 39.99; Eye Witness Encyclopedia of Nature 8 and upwards, Pounds 39.99. Both from Dorling Kindersley. Tel: 0171 836 5411

Encarta 7-18, Pounds 50 (approx) from Microsoft. Tel:0345 002000* For details of the NCETASE roadshow and Web page contact Maureen Byrne on tel: 01203 416994