The foundational document of the current science standards movement--the "Framework for K-12 Science Education"--is grounded in research about how students from diverse backgrounds learn science and the conditions under which they can participate in knowledge-building activities of the discipline. We argue that teacher educators should use powerful principles for instruction, derived from the research referenced in the "Framework," to inform the design of courses and other preparatory experiences for novices. This implementation strategy contrasts with an alignment approach, in which novices would be asked to familiarize themselves with the "Next Generation Science Standards" ("NGSS"), integrate student performance expectations into lesson plans, and teach activities similar to those described in the "NGSS." We describe the more principled approach as a "three-story challenge" in which students, teachers, and teacher educators have responsibilities to learn and to take up new roles in the educational system that are fundamentally different from the status quo.