Despite Common Core, States Still Lack Common Standards
"Note that an A or a B does not indicate a relatively high performance by students in the state. Rather, it indicates that the state’s definition of proficient embodies higher expectations for students. It is best thought of as a high grade for “truth in advertising,” telling citizens frankly how well students are performing on an internationally accepted scale, just as states have pledged to do by joining the CCSS consortium. See the methodological sidebar for further details."