Abstract
This study was initiated in an area of school science, earth science education, which has been little explored. A sample of 493 Portuguese pupils aged 10‐11 and 14‐15 (at the beginning and end of secondary schooling) was involved. The study used interviews and a written questionnaire to probe the ideas about the origin and development of earth and life which were held by pupils who had not been taught those topics, the conjecture being that pupils would have developed their own beliefs. A significant number of commonly‐held ideas were found which were independent of those relating to the scientific consensus. Using suggestions provided by existing teaching‐learning models, guidelines are developed which should help learners to challenge their homespun views and promote their own conceptual changes.