This article describes the possibilities offered by the online assessment system Etude to achieve the benefits of formative assessment. In order to find out the way this works in practice, we carried out an experiment with the use of Etude for formative assessment in the course on collaborative report writing. Results show that online formative assessment has a lot to offer for improving students' learning process, but that a number of aspects should be taken into account in order to achieve the benefits. (Contains 1 table and 3 figures.)