A great deal of research has shown that teacher quality does matter. Although most teachers work hard doing the best they can, some teachers do their job successfully and others fail to do so. Depending on teachers\' classroom teaching activity, students\' learning differs significantly. There is a huge gap in student achievement between teachers who are highly qualified and who are not. In order to improve teacher quality, it is important to identify and classify successful and unsuccessful teaching. In this article, I argue that professional teacher knows the content, student, and teaching method very well and be able to teach the content to students successfully. I also use a metaphor to express the successful teacher―the custom designer. Finally, I present a value-added categorization of teacher by classroom teaching as shown in Table 1.