The research concerns the study of the effects of different practices of formative assessment on student self-regulation, in the context of inquiry-based science teaching. An indicator grid is constructed to analyze in situ processes, and two teaching situations are compared. The first corresponds to formative assessment such as teachers implement it in their daily practice. The second concerns the assessment practices implemented by the same teachers the following year, after a reflective workshop with the researchers. After confirming through a statistical analysis that teachers implement different modalities of formative assessment from one year to the next, we describe the evaluative practices of teachers and their effects on students. Our results show a better balance in the use of different formative assessment modalities by the teachers in the second situation and a more efficient self-regulation by the students in the proposed task.