There's something ironic in the idea of a CD-Rom, however interactive its content, that engrosses children in finding out why they should be up and doing. Join the Activaters manages, none the less, to get its four key messages across in a convincing manner. Key stage 2 pupils will learn that they shouldn't skip breakfast or identify with the "Dolittles" - a family of couch potatoes - and that they should eat plenty of fruit and vegetables and take regular exercise. In the course of visiting a virtual leisure centre or shopping in cyberspace, they'll also get useful practice in maths, geography and English. Join the Activaters is being distributed by the Food and Drink Federation to 25,000 primary schools.