In this study, the authors analyse the contribution of a teacher education setting based on ICT (email and forum) in developing professional knowledge of one prospective mathematics teacher, looking especially at tasks and forms of communication. The results show that, in addition to exercises, the prospective teacher began to suggest more open and challenging tasks, and to promote contributive communication in his classroom. In planning his lessons, the prospective mathematics teacher’s professional knowledge showed improvement in the diversity of tasks that he adopted, in the attention he gave to student activity, in the adequacy of instructional materials that he used, and in the forms of communication that he promoted, which involved more students in the classroom activities.