The right question in the debates about class size: Why is the (positive) effect so small?

Abstract

The first important observation is that the research has little impact on policy and the debates that surround this topic. There are some implementations of class size reduction where the effects on achievement are negative – these are usually when they are hastily implemented, necessitating employment of lower quality or untrained teachers such as in the Californian reduction (Bohrnstedt, Stecher, and Wiley, 2000), but nearly all studies show that reducing class size increases achievement. For example, Zyngier (2014) reviewed over 112 studies including what could be called the ‘fundamental’ studies: Student-Teacher Achievement Ratio (STAR) Finn and Achilles (1999), Glass and Smith (1978), Bl..