The governors of Oklahoma and South Carolina signed bills repealing the Common Core standards, guidelines for children’s achievement in reading and math between kindergarten and high school graduation. Both states had been among the 46 and the District of Columbia that had adopted the standards, written by a group of educators and other experts convened by the National Governors Association and the Council of Chief State School Officers. But as resistance grew in their states, lawmakers moved to replace them with standards developed within the states. Gov. Nikki R. Haley of South Carolina signed that state’s bill last week, and Gov. Mary Fallin of Oklahoma signed a bill that would require educators in the state to set new standards to replace the Common Core.