Participation is the principal theme in Fun and Learning in the Countryside, an activity book from the National Trust. There are 100 suggested things to do, such as role-playing the interactions of frogs and their predators or measuring the frequency and angles of waves. Others involve particular life forms - enacting thefood web connecting invertebrates to plants or recording the tunes of song birds. Fun and Learning in the Countryside costs pound;8.50 + pound;2.50 pamp;p from Vector Services (National Trust Education), 13 Denington Road, Wellingborough, Northants NN8 2RL. Tel: 01933 445600. Website: www.nationaltrust.org.ukeducation