Formative assessment is a central factor in students' learning process, by continuously providing feedback, students are given the opportunity to develop in their learning. By conducting a survey of teachers' perspectives and experiences, we want to contribute with a deeper insight into how formative assessment is applied in practice, its possibilities and the challenges that may arise. The purpose of the survey is to highlight teachers' understanding of formative assessment, how they explain its purpose and function in teaching, and what conditions and obstacles they encounter in the work of applying formative assessment in practice. The question is: How do teachers view the importance of formative assessment and its application in practice, within the framework of cooperative learning? The method used for the implementation of the study and for data collection was semi-structured interviews. Based on the information collected during the interviews, it is noted that formative assessment is a central aspect in students' knowledge development as it is adapted in teaching based on the needs and conditions that the students have.