The new common core standards for mathematics demand that students (and teachers!) exhibit deeper conceptual understanding. That's music to the ears of education professor John Tapper, who says teachers have overemphasized teaching procedures--and getting right answers. In his new book, "Solving for Why," he makes a powerful case for moving beyond right and wrong and exploring what students understand, where they are struggling, and most important, why they are struggling. The author talked with Tapper about concrete-representational abstract assessments, or CRA, a tool that does just that. It's easy to do, and it provides a sophisticated portrait of kids' models for mathematical concepts. That ties in with the Core, and with Tapper's call for teachers to focus on the learner.