In April 2013, the Next Generation Science Standards (NGSS) were released.1 They build on the (now almost 20-year-old) AAAS Benchmarks for Science Literacy,2 and National Science Education Standards,3 in that they provide guidance about what all students should know and be able to do with that scientific knowledge. The NGSS are designed to bring insights from newer research on how students learn science4 into curricular design and delivery, and to provide a standards structure that emphasizes a deeper understanding of a smaller, yet more central number of core concepts. In a world where facts are just a click away, it is the context of the knowledge and the ability to use it that will become ever more
important.
The NGSS are based on the NRC Framework for Science Education5 that is composed of three strands: disciplinary core ideas, crosscutting concepts, and science (and engineering) practices. Disciplinary core ideas (DCIs) are significant ideas of broad importance to the discipline; they have explanatory power, are generative of more specialized ideas, and can be developed over time from K−12 (and beyond). The DCIs in the framework are necessarily of a fairly large grain size. For example, the first physical science core idea PS-1, Matter and its Interactions is guided by the question “How can one explain the structure, properties, and interactions of matter?” The development of PS-1 begins in the early elementary years with the idea that “matter exists as difference substances as exhibited by their observable properties”5 and progresses through high school where “the sub-atomic model and interactions between electric charges can be used to explain interactions of matter”.5 This research-based longitudinal and developmental elaboration of a core concept is often termed a learning progression.6
As their name implies, the crosscutting concepts are those ideas that reach across disciplines to tie them together. Patterns,