Three years after calling for a reordering of elementary and middle school math curricula, the nation's largest group of math teachers is urging a new approach to high school instruction, one that aims to build students' ability to choose and apply the most effective problem-solving techniques, in the classroom and in life. Cultivating those skills will make math more useful, and more meaningful, to students, the National Council of Teachers of Mathematics (NCTM) argues in a document scheduled for release this week. The high school document has both a different purpose and a different structure. It is not a suggested set of content standards, but rather a framework that attempts to show how skills that the NCTM considers essential--reasoning and sense-making--can be promoted across high school math. The NCTM's high school guidelines explain how reasoning and sense-making can be applied in different areas of math. They also offer numerous examples of how such applications might play out in the classroom, presented through model dialogues between teachers and students covering math lessons.