Using formal assessment to measure student knowledge can come at several different points during your course plan. Assessments preformed before a course, while you are teaching the course and after you are finished teaching the course are all valid and helpful to a teacher, yet each serve different purposes. Understanding each assessment type is important to helping teachers fine tune their teaching skills. It can be beneficial for a teacher to give a student an assessment before teaching a new course. This will help the teacher know what information the students already know about the subject to be studied, and help the teacher focus her lessons. This type of assessment is generally done through class discussion.