LessonLab Viewer™ is a powerful software that allows the distribution, annotation and discussion of videotaped data over the internet. The software is specially designed to promote the professional discourse on classroom teaching. Groups of expert didactitians, teachers, university students and teacher trainees can share their observations and exchange their ideas by discussing classroom video data and additional material in this web-based learning platform. At the University of Zurich we are conducting a number of case studies using this software. First experience shows that the implementation of new tools can promote deep learning if the didactical arrangements support the new facilities and provide a strong learning support.