Sharon and Tracey Do London - A Journey through the Jubilee Line Extension Project. CD-Rom from TAG Developments Ltd, 25 Pelham Road, Gravesend, Kent DA11 0HU. Tel: 0800 591262.

Dual platform (PC and Mac) version pound;15.99 (+VAT and p+p). London’s Thames - The Living Working River. CD-Rom available from ThamesClean, co Tidy Britain Group, 12-13 Hatton Garden, London EC1N 8AN. Tel: 0171 831 4484. PC version pound;29.99 (pound;2.50 p+p).

London is the link between these two CD-Roms. Sharon and Tracey Do London is aimed at eight to 11-year-olds and presents an interesting and useful look at the major engineering feat that is the Jubilee Line extension. London’s Thames is altogether stronger stuff, a broad-based overview of the capital’s river with a slight bias to promoting its recent cleaner state. This CD-Rom is suitable for 11-14-ish (the relevance of the “ish” will be clear later).

Sharon and Tracey are not birds of a feather, or even any other pair of Cockney lasses. They are two hulks of boring machines that scoured out the tunnels to create the new Jubilee Line extension, now expected to open in spring 1999. This, apparently, was the name given to them as a result of a competition. The mammoth scale of the machines, and indeed the whole operation, are central to the theme of the CD-Rom.

As Alistair Siddons, public relations executive for London Underground, says: “the sheer scale of the project is normally beyond people’s scale of reference; they just can’t imagine the size.” This - the 13km of twin-tunnel line, the five brand new stations and six major refurbished stations - are all on the doorstep, too. At least on the doorstep of the 500 schools nearest to the scheme which have all been sent copies.

Alistair Siddons may have less trouble convincing people of the size of the project than explaining its late opening. Big cost hikes and accompanying delays are seemingly part and parcel of large engineering projects such as the Jubilee Line - all of which is a matter of some concern a mile or so down the river, where the Millennium Dome is under construction. Completion of the Jubilee Line is seen as crucial to the dome’s success.

The CD-Rom will also be of interest beyond east London. It includes video clips, photo explanations, diagrams, and so on. A series of short quizzes adds to the fun and learning potential. I suppose good fun, as captured by the title, is what you will remember about the approach.

It’s the fun element (a chap in a toga who wanders on and tells us odd facts) that might prevent London’s Thames from being taken too seriously beyond key stage 3. Those in the “14-ish” age range might feel a little patronised, which would be a pity because the information is fascinating and pulls together themes from across the board (geology, economics, history, and so on).

Barriers between areas are broken down, with the Thames flowing through as the linking theme. The design of the content makes this an ideal resource for students who enjoy learning in a visual way. Screens carry illustrations and copy that help understand links between elements of the life of the river.

Geographers will especially enjoy the aerial photography section, although it’s not always easy to grab the enlargement you require. The provenance of the video, a clutch of environmental agencies, is not overly obvious. Indeed, I could find no mention of that perennial favourite - salmon reappearing in the river.

All in all London’s Thames is a simple-to-use, factually based resource that is, although not vital, very interesting if you’ve got the time.

Ultimately, you may wish these two topics will remind students (especially beyond London) what an amazing place our capital is - too big, too dominant, too diverse. Well maybe - but pretty incredible too.