In this plenary we will briefly look at the outcome of a large EU project about formative assessment (ASSIST-ME project). The project studied four kinds of formative assessment in relation to teaching and learning inquiry science: ’on-the-fly’, peer-to-peer, group discussion and written assessment. To get some experience with these assessment approaches, we will examine a project-based chemistry course at the University of Utrecht where the task was to design a new ‘drug’. We will participate in an anonymous Internet based poll of when formative assessment should be used and what kind is relevant for various stages of the Utrecht project-based course. We’ll conclude by aligning our poll results with those based on research about using formative assessment for PBE and seeing how a model from the ASSIST-ME project provides an overall view of the use of formative assessment in PBE.