In the UK practical work has traditionally played a very significant role in school science education. In the early part of the twentieth century Armstrong promoted the heuristic approach to science teaching with its considerable reliance upon laboratory work. A survey by Beatty and Woolnough (1982) revealed that in 83 per cent of their sample of schools, between forty and eighty per cent of the time in 11-13 science classes was spent doing practical work. Teachers clearly thought of practical work as an important activity and yet paradoxically it contributed little to their science assessment.