 Formative assessment occurs when teachers feed information back to students in ways that enable the student to learn better, or when students can engage in a similar, self-reflective process.The evidence shows that high quality formative assessment does have a powerful impact on student learning.Black and Wiliam (1998) report that studies of formative assessment show an effect size on standardized tests of between 0.4 and 0.7, larger than most known educational interventions.