This paper proposes a platform model to support teacher professional development. From a study of exchanges between teachers on Web forums we examine two facets of knowledge exchange, usual teaching practices and problem solving, and how they can be managed on a unique web platform. We use a task/method paradigm for knowledge elicitation about usual teaching practices, driven by the exchanges between teachers and capitalized into individual memories. For problem solving we use an IBIS-like approach (problem, solution, argument) and REX-like cards to structure the problem and solution description. The important problem of knowledge evaluation is treated with a three-level evaluation (opinion, usefulness and difficulty). The teacher's profile and its central role in connecting teachers is described. For knowledge classification, because a consensus is difficult in this domain, we propose a mixed approach between structured classification techniques (taxonomies) and unstructured techniques (folksonomies).