In this thesis I intend to write about how five primary school teachers reflect on formative assessment and how the formative assessment of students can take place practically according to teachers. My questions are: How do the five teachers perceive on formative assessment as a pedagogical approach? How do the teachers do to assess students’ knowledge? In what way do the teachers give feedback to students?The work is based on qualitative interview method where five elementary school teachers were able to reflect on their classroom practice with a focus on formative assessment. The theoryI have chosen to work from is the so-called five key strategies of formative assessment.These strategies are about; clarifying, communicating and creating understanding of the learning objectives and criteria for progress, to achieve effective classroom discussions, activities and learning data to show that learning has taken place, to provide feedback for learning forward, toenable students to become learning resources for one another, and to enable students to own their own learning. The results of the interviews showed that a formative approach lasted in a more implicit than an explicit meaning in classrooms. The formative approach was fairly a new phenomenon and had not begun in the larger extent of the interviewed teachers’ schools yet. Assessment materials were used to clarify the learning outcomes for students. Methods andactivities in the classrooms took place on a smaller scale in the form of discussions between students. Self-assessment was considered by most teachers as something they could not imagine or was considered to be too difficult for the students because of the children's young age. The results also showed that there is a great need to make time for evaluation and to gain knowledge of articulate, reflective subject issues to provide students with