The Common Core initiative has been in the works for some time. A state-led effort, it began in 2009, fueled by the CCSSO and the National Governors Association. Kentucky was the first state to officially adopt the standards, in 2010, followed by 44 other states and the District of Columbia. The only states not to adopt the standards are Alaska, Nebraska, Texas, and Virginia. (Minnesota adopted the English standards but not the math standards.)
Prior efforts to set common national standards had failed, in part because they came from the federal government rather than from the states themselves. The hope this time was to have rigorous standards that cross state boundaries and that are coherent across grade levels and subjects – allowing students to build from year to year on prior understanding.
Former standards in many states "were a mile wide and an inch deep," says Heath Phillips. "We're trying to go to the opposite – a few inches wide but a mile deep. We're trying to build those critical-thinking and problem-solving skills, and students' ability to apply those in various real-world situations."