This paper reports results of the deployment of a learning analytics dashboard in the context of introductory Maths, Physics and Chemistry courses in the first year of the Engineering bachelor of a Swiss technical university. Informed by research on self regulated learning, learning analytics dashboards and the social practice of learning in Higher Education, the tool includes a learning diary feature where students report their progress and the difficulties encountered in solving the course exercises. Both students and teachers have access to a dashboard showing an overview of the class progress and difficulties, the student view including personalized feedback. We present usage and survey data, and show how these help to identify key intervention principles to maximize the impact of learning analytics dashboards on the practice of students and teachers.