ARCs are Activities with Rigor and Coherence. Each ARC is a series of lessons that addresses a mathematical topic and demonstrates the vision of *Principles to Actions: Ensuring Mathematical Success for All*. ARCs scaffold effective teaching and support enactment of the eight Mathematics Teaching Practices articulated in *Principles to Actions* as well as the instructional guidance set forth in *5 Practices for Orchestrating Productive Mathematics Discussions*. ARCs integrate a wide array of NCTM resources to optimize opportunities for learning, including Illuminations and Student Explorations in Mathematics. ARCs also include community features that offer opportunities for social interaction. Engage in online discussions with other math educators, post a comment, and give feedback with ratings and reviews.