At its core, science is about making sense of the world around us. Therefore, science education should engage students in that sense-making process. Helping students make sense of disciplinary core ideas and crosscutting concepts by engaging in scientific practices is the key innovation of the "Next Generation Science Standards" ("NGSS"). These standards make explicit the various sensemaking practices of science and link those practices tightly to content learning. To move toward the vision of the NGSS, teachers need clear examples of what this engagement looks like in the classroom. This article shows how developing and using models can anchor the other practices identified in the "NGSS." Models in science serve as the functional unit of scientific thought. The model--broadly defined as a set of ideas about how something in the world works--motivates and constrains the kinds of "questions" one asks about phenomena, the kinds of "investigations" one carries out, and the ways of "analyzing and interpreting data"; and, ultimately, the model guides any explanations for phenomena that one develops. Moreover, a learning environment centered on models and modeling can support a range of opportunities for "gathering and communicating information," engaging in "argumentation" and, in some cases, applying "mathematical reasoning." (The terms in quotes are the practices as defined in the "NGSS".) To illustrate the potential for the practice of developing and using models to serve as an anchor for all of the "NGSS" practices, the authors present here a coherent unit on natural selection. It is their hope that this article will show that a core model can anchor science instruction that includes all of the practices called for in the "NGSS." Anchoring the practices to one another in service of developing deep content understanding is important to maintaining strong coherence in a lesson sequence. It also prioritizes and operationalizes the sense-making process so central to science that is at the heart of the "Next Generation Science Standards."