“The greater rigor embedded in the new Common Core State Standards is likely to be squandered—with little effect on student achievement—if the standards themselves are not well-implemented, and if the content of the curriculum, instructional materials, classroom instruction, and professional development are not top-notch, integrated, and consistent with the standards,” write Michael Casserly in Pieces of the Puzzle. The study looks at at Charlotte-Mecklenberg, a consistently high-performing district, Atlanta and Boston, which have showed improvement in the last decade, and Cleveland, which hasn’t improved.