Among the most daunting assignments Ms. Lowery took on was the introduction of the Common Core, a national set of standards adopted by 44 states and the District of Columbia that define what K-12 students should know at the end of each grade. The standards stress the development of critical thinking skills and a more rigorous approach to traditional subjects like reading, math and science. But some teachers and parents criticized the tests used to evaluate students' performance, saying they were too difficult, caused children undue stress and took up so much classroom time to prepare for that they ended up crowding out courses like art and music. Ms. Lowery listened carefully to the complaints, looked at how they might be addressed, then worked collaboratively to resolve them in ways that allowed the state to continue moving forward. Consequently, Maryland experienced nothing like the Common Core backlash seen in other states.