We have put forward an approach to online collaborative discussion of software development problems based on Argumentation theory. Having records of past discussions can significantly help solve problems in new projects, and CBR techniques are used to retrieve the most similar cases. However, long discussions on past projects still contain too much information to provide support in new discussions. To address this problem, in this paper we introduce the idea of explanation templates that are able to summarize past experiences, particularly for risk management discussions. We formalize this notion of template, introduce the main templates we have developed to support explanation of past experience with risk management, and report the results of a case study on a realworld software project to assess the usefulness of those templates.