Knowing cause and purpose can enable a useful flexibility in thought and action that is more likely to produce a desired outcome. Some teachers, particularly trainees, new teachers, and those without a strong background in technology, may not address this kind of knowledge. Could children's technology textbooks provide a model of practice for such teachers? This study examined 24 books intended for children aged 7-11 years in Design and Technology lessons in England. It was found that some books had little potential as models of practice in this regard. Others showed some concern for cause and purpose in connection with conceptual knowledge. Few, if any, addressed cause and purpose to do with procedural knowledge. It was concluded that these textbooks varied greatly in their potential to guide teachers to address cause and purpose and to exemplify practice. The danger is that new or non-specialist teachers may be guided by a book that shows no explicit concern for particular kinds of cause and purpose. The problem is that such teachers may not recognise the deficiencies of such books. Some implications for teacher training are discussed. (Contains 1 figure and 1 table.)