"Computer Images for Lesson Support" (CILS) is a module for primary teacher education that aims at educating prospective teachers in designing multimedia-learning environments, with the aid of the Logo program MicroWorlds, and using it with children. Quantitative and qualitative data were collected among 44 student teachers during their designing and teaching activities. Data were analyzed by means of descriptive and correlative statistics as well as content analysis. The following influences on students' learning were found: prior learning in computer use; students' learning orientation; the nature of their cooperation in groups; the module itself and how it was embedded in the teacher education curriculum; the technical infrastructure and staff cooperation available in the schools where the students did their student teaching; and the students' learning experiences in those schools. Conclusions about the CILS module and the underlying approach to developing prospective teachers' competence in educational computer use are presented and implications for teacher education and further research are discussed. (Contains 1 table and 2 figures.)