Research on Common Core standards impact on education

Teaching and learning has changed significantly under the Common Core State Standards, according to a study of five states. Math teachers, for example, are focusing more on real-world applications and conceptual understanding, and English teachers are exposing students to more nonfiction.
Kane, T. et al.  (2016). Teaching higher. Cambridge, MA: Harvard University Center for Education Policy Research.
http://cepr.harvard.edu/files/cepr/files/teaching-higher-report.pdf