A new set of "publishers' criteria" crafted by the lead writers of the common core in mathematics is intended to help reshape K-8 instructional materials nationwide by spelling out what it means to align faithfully with the math standards adopted by 45 states and the District of Columbia. The document blends general guidance with some real specifics, such as suggesting how long textbooks should be--fewer than 200 pages at the elementary level--and at what grade level it's appropriate for chapter tests to address particular topics. A key mantra is the standards' push for focus--covering fewer topics in greater depth--which the authors acknowledge "can seem like hard medicine for an educational system addicted to coverage." Some in the education and publishing fields have offered generally favorable reviews of the 24-page document, which has been endorsed by several prominent organizations that provided feedback on early drafts, including national groups representing governors, chief state school officers, state boards of education, and large urban districts, as well as Achieve, a Washington-based nonprofit organization that managed the process for developing the Common Core State Standards. A similar document for the common English/language arts standards--first issued last year and endorsed by the same five organizations--was revised this spring.