 In that sense, formative assessment is diagnostic.To employ formative assessment in the classrooms, a teacher has to make sure that each student participates in the learning process by expressing their ideas; there is a trustful environment in which students can provide each other with feedback; s/he (the teacher) provides students with feedback; and the instruction is modified according to students' needs.In math classes, thought revealing activities such as model-eliciting activities (MEAs) and generative activities provide good opportunities for covering these aspects of formative assessment.