The purpose of the present work is to describe the progression in the conceptions of prospective primary teachers about school science content while they were participating in three teacher education courses following the same constructivist oriented strategy. The participants' written output was analyzed in various categories--selection of content, types of content and their relationships, levels of complexity, and presentation of content to pupils. There was evidence for some progress in their conceptions of the content from a traditional view to another that we termed intermediate since it did not reach the vision that we consider to be the most complex. Finally, we present a General Itinerary of Progression on school content that could serve as a referent for initial teacher education.