The Common Core State Standards in Mathematics

In 2009, 48 out of the 50 states in the U.S. came together under the leadership of the National Governors Association (NGA) and the Council of Chief State School Officers (CCSSO) to write school standards for Mathematics and English Language Arts that would ensure students leaving high school are ready for college and career. The Common Core State Standards (CCSS) were released on 2 June 2010, and they have been adopted by 45 states. Twenty years earlier, in 1989, the National Council of Teachers of Mathematics made the first move in the modern era towards a common understanding of school mathematics [7]. Before that time curriculum varied among the nation’s numerous school districts. The NCTM standards were not themselves an act of government, but in response to them the governments of the 50 states started developing their own standards, bringing a measure of consistency to the mathematics curriculum within states. However, consistency between states proved elusive and in the years after 1989 state standards diverged greatly. For example, Table 1 shows the 2006 distribution of grade levels at which 42 state standards introduced addition and subtraction of fractions: