A whirlwind of activity surrounds the topic of teaching and learning mathematics. The driving forces are a combination of changes in assessment and advances in technology that are being spurred on by the introduction of content in the Common Core State Standards for Mathematical Practice. Although the issues are certainly complex, the same forces driving the change initiative are fortunately providing clear directional arrows toward success. Technological advances are expanding the ways mathematics teachers can assess students' learning. These assessment advances in technology will affect every state, and the end result is that classroom assessments will become more rigorous. The shift in classroom instruction and assessments will demand that students learn and perform differently. To meet this shift in assessments and demand for rigor, classroom instruction must change. Luckily, there is also direction provided for those mathematical shifts in the form of the Common Core's Standards for Mathematical Practice. The practices associated with the standards, when used intentionally and deeply, promote mathematical rigor. To be attained, however, mathematical rigor must be clearly understood as it relates to the practices and forthcoming assessments. This article defines rigor, provides a rigor comparison chart showing current practices versus future demands, and provides two sample problems that accentuate the differences between between a current classroom and a future, rigorous classroom.