In this article, we argue for a new rationale for the science curriculum that is more coherent and more useful than the crosscutting concepts of the Next Generation Science Standards (NGSS). In an effort to provide both clarity and justification for the science curriculum, we contend that a framework based on the idea that there are six "styles of scientific reasoning" will better guide teachers, curriculum designers, and assessment developers. While the NGSS set out to articulate the learning outcomes of the science curriculum as a set of performance expectations within three major scientific disciplines, we argue that the crosscutting concepts have no scholarly basis for what the sciences have in common. The consequence is that the NGSS make no case for the over-arching importance of specific performance expectations, include cross cutting concepts inconsistently across different grades, and provide no rationale for each standard. In contrast, we argue that the framework of "styles of scientific reasoning" does offer a coherent curriculum framework for the science curriculum from grades K through 12, a justification for each performance expectation, and a vision of how each standard might support the development of scientific reasoning. Implications for curriculum designers and educators are discussed.