I studied cognitive/educational psychology at the University of Amsterdam (graduated cum laude). After my studies I joined Delft University of Technology and after this I became researcher, later on senior researcher, at both the University of Amsterdam and the Eindhoven University of Technology. In 1986, I received a PhD from the Eindhoven University of Technology on the topic "problem solving and knowledge representation in physics for novice students" (supervision D.W. Vaags, G.J. Mellenbergh, C. Hamaker). In 1992, I became associate professor at the University of Twente, department of Instructional Technology, and since June 1998 full professor at the same department. From April 2001 to April 2002, I have hold a temporary professorship at the Knowledge Media Research Center (Insititut für Wissensmedien) at the University of Tübingen, Germany.From mid 2013 until September 2018, I was Dean of Education for the Masters programme Educational Science and Technology. I am elected member of the Academia Europaea and fellow of the AERA and ISLS. In 2023 I received the EARLI oeuvre award.