Continuous educational improvement is a hot topic in both academic circles and public concerns. Academic achievement is influenced by many aspects, such as pupil-teacher ratio, disciplines, instructional input, family education, individual efforts, classmates and other off-campus conditions. In addition to all these factors, many people believe that changing class sizes is the easiest way to develop education. However, class size is one of the most important factors in determining academic success rather than the most crucial one. This essay will discuss both class size reduction and other factors that influence educational progress, and then suggest the multi-influence of all possible elements that determine academic achievement. Class sizes benefit the primary phase but do not show a significant contribution to academic performance in the long term. Eric Hanushek of the Hoover Institution at Stanford University agrees that low pupil-teacher ratios can bring early advantages to students. But at the same time, he argues that there is a lack of data demonstrating the persistence of gai...