With such publications as "Curriculum and Evaluation Standards" (1989) and "Principles and Standards for School Mathematic" (2000), NCTM has played a significant role in defining a vision for school mathematics. In particular, the Curriculum Principle (NCTM 2000, pp. 14-16) described the need for students to learn important mathematics (focus) that is interconnected within and across grade levels (coherence). In addition, the Learning Principle (NCTM 2000, pp. 20-21) described the need for students not only to develop conceptual understanding and procedural fluency but also to apply this knowledge (rigor). Building on this foundation, the creators of the Common Core State Standards for Mathematics (CCSSM) used focus, coherence, and rigor as design principles to frame these standards (CCSSI 2010). That is, they sought to create a curriculum that included important interconnected mathematics and represented a balance of conceptual understanding, procedural skill, and application. Understanding the need to support teachers in implementing CCSSM, educators and researchers have presented these design principles as shifts, or "key changes required by the Standards" (Student Achievement Partners 2012b, paragraph 2). Because many math teachers are unsure of what these standards entail in regard to instruction (Gewertz 2013), these shifts--focus, coherence, and rigor--provide a means for understanding the instructional changes needed for implementing the Common Core. To understand the shifts, the authors first offer a description of the terms focus, coherence, and rigor. Next, they look at how to apply these shifts in a classroom setting. Finally, they solidify this understanding through a vignette that illustrates this application of the shifts.