45 states have raised their English and math standards since 2011, a result of adopting Common Core State Standards, according to Education Next, a journal reporting on K-12 education.

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Education Next says this change is a significant improvement from the low standards set by most states following the implementation of the 2001 No Child Left Behind law.
Education Next has graded states on the rigor of their statewide tests for fourth and eighth graders in English and math for several years. While six states received an “A” grade in 2005, that number jumped to 24 in 2015. And while in 2005 17 states received a “D” or “F” grade, in 2015 only one state (Texas) received a “D” grade and none received an “F.”
Those 24 states which received an “A” grade include Alaska, Arizona, Arkansas, Colorado, Connecticut, District of Columbia, Georgia, Idaho, Illinois, Kansas, Maine, Maryland, Mississippi, Montana, New Jersey, New York, New Hampshire, New Mexico, North Dakota, Pennsylvania, Rhode Island, South Dakota, Utah, and Vermont.
Two states, Wisconsin and Florida, are not included in the data because they had not reported test results by the middle of January when the data was compiled.
Education Next published a table showing the rigor of state testing from 2003 to 2015. Forty-eight states and the District of Columbia are included in the table, available at http://educationnext.org/after-common-core-states-set-rigorous-standards/.
However, the change in standards has not led to greater achievement by students. In most states, about one-third of students taking their first Common Core Standards-aligned tests in the spring of 2015 passed, and about 2/3 failed.
Critics of the improved state standards, who wrote to the journal, question whether present-day curricula supports the new state standards; whether the new standards are reasonable; whether teacher-made tests are aligned with the new standards; whether the previous statewide tests used as comparisons are aligned with what is tested on the new tests; and whether teachers have been properly trained to prepare students for these new tests.