Dodona: learn to code with a virtual co-teacher that supports active learning

Dodona (dodona.ugent.be) is an intelligent tutoring system for computer programming. It bridges the gap between assessment and learning by providing real-time data and feedback to help students learn better, teachers teach better and educational technology become more effective. We demonstrate how Dodona can be used as a virtual co-teacher to stimulate active learning and support challenge-based education in open and collaborative learning environments. We also highlight some of the opportunities (automated feedback, learning analytics, educational data mining) and challenges (scalable feedback, open internet exams, plagiarism) we faced in practice. Dodona is free for use and has more than 36 thousand registered users across many educational and research institutes, of which 15 thousand new users registered last year. Lowering the barriers for such a broad adoption was achieved by following best practices and extensible approaches for software development, authentication, content management, assessment, security and interoperability, and by adopting a holistic view on computer-assisted learning and teaching that spans all aspects of managing courses that involve programming assignments. The source code of Dodona is available on GitHub under the permissive MIT open-source license.