is a researcher at De Kempel Institute for Teacher Education. Her research focuses on the use of portfolio assessment as a tool to enhance elementary school students' motivation and self-regulation. Marjan Vermeulen is professor at the Welten Institute of the Open University The Netherlands. Her research interests lie in the professional development of teachers and innovative teacher behavior. Jos Castelijns is a senior researcher at De Kempel Institute for Teacher Education. His research concerns teacher education, curriculum development, assessment and motivation. Rob Martens is professor at the Welten Institute of the Open University The Netherlands. His research interest include multimedia learning and the influence of multimedia learning on students' motivation.