The NGSS are research-based, K-12 science content standards developed by states to improve science education for all students. The standards incorporate three important dimensions (crosscutting concepts, disciplinary core ideas, and science and engineering practices). These dimensions are combined to form each standard and are intended to promote classroom learning experiences that help students stimulate interest in and develop a cohesive understanding of science over time.  

Crosscutting concepts encourage students to make connections between four science and engineering domains (Physical Science, Life Science, Earth and Space Science, and Engineering Design) and develop a scientifically-based worldview. These concepts are applicable across all four domains and include, for example, cause and effect, proportion and quantity, and energy and matter.  

Disciplinary core ideas are the key ideas that have widespread significance and impact on the four science and engineering domains. These core ideas anchor K-12 curriculum, instruction, and assessment in the foundational elements of science and engineering.  

Science and engineering practices allow students to apply their knowledge of crosscutting concepts and disciplinary core ideas though inquiry, investigation, design, and development. The practical application of these practices helps students understand the relevance and importance of STEM to real-world challenges.  

These new, three-dimensional standards pose unique challenges to assessment and demand new ways of measuring science learning to ensure students are being assessed on complex science thinking, not just superficial knowledge. SIPS will produce tools and resources aligned to NGSS, affording states the option to apply the principled-design framework and processes to their state-specific academic standards or, if they are a NGSS state, to adopt the materials that are developed in alignment. Through the use of detailed guidance and tools, key facets of the state-specific work completed through this project will be adaptable to other states’ contexts and sustainable beyond the life of the project.

The Framework (NRC, 2012) presents a vision for three-dimensional science learning (Pellegrino et al., 2014) in which students are to make sense of phenomena or design solutions to problems using disciplinary core ideas, scientific and engineering practices and crosscutting concepts. Disciplinary core ideas (DCIs) represent the powerful ideas of the disciplines of Earth and space sciences, physical science, and life science, and are used in explaining a range of natural phenomena. For instance, the physical science DCI of matter and its interactions helps to explain what everything is made of and predicts why things happen in the natural world. Within biology, evolution serves as a DCI that explains the diversity of life on Earth. Crosscutting concepts, such as patterns, cause and effect, scale, and systems are ideas that occur within and across disciplinary boundaries and have explanatory value throughout much of science and engineering. Patterns, for instance, exist everywhere and occur in biological, chemical, and Earth systems and scientists in all fields seek explanations for observed patterns as they make sense of phenomena. Scientific and engineering practices are the everyday ways of knowing and doing which scientists and engineers employ to study and explore the natural and designed worlds.

Both scientists and engineers engage, for example, in the practice of developing and using models. Scientists use models to understand and explain phenomena; engineers use models to develop and analyze systems as well as develop and test designs. The Framework vision, derived from a rich research base on how students learn science (see, for example, NRC, 2007) puts forth that in order to learn science, you need to do science by making use of all three dimensions. It is making use of the three dimensions that reflects the knowledge-in-use perspective within the Framework and which guided development of the NGSS.

Accordingly, the NGSS expresses standards as performance expectations that integrate all three dimensions of science proficiency. Each NGSS performance expectation integrates a science or engineering practice, a disciplinary core idea, and a crosscutting concept into a single statement of what is to be assessed at the end of a grade level or grade band. It incorporates all three dimensions of knowledge-in-use by asking students to apply disciplinary knowledge and make connections to a crosscutting concept as they engage in a science or engineering practice to make sense of phenomena or design solutions to problems. For example, an NGSS performance expectation for middle school physical science that focuses on the important idea of chemical reactions is stated as: Analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred. Another performance expectation related to chemical reactions addresses different dimensions and is stated as: Develop and use a model to describe how the total number of atoms does not change in a chemical reaction and thus mass is conserved. In NGSS nomenclature, these are referred to as MS-PS1-2 and MS-PS1-5, respectively.

Performance expectations are complex and considered summative goals, and therefore need to be learned over time and through a sequence of carefully designed lessons and units. At the elementary level, students are expected to develop proficiency across the year; whereas at the middle and high school levels, proficiency is attained across the grade band. Given the multi- dimensionality of the performance expectations and their broad scope, it is no easy task for teachers to gauge student progress toward achieving them.


National Research Council. (2007). Taking Science to School: Learning and Teaching Science in Grades K-8. Washington, DC: The National Academies Press.

National Research Council. (2012). A Framework for K-12 Science Education: Practices, Crosscutting Concepts, and Core Ideas. Washington, DC: National Academies Press.

Pellegrino, J. W., Chudowsky, N., & Glaser, R. (2001). Knowing what students know: The science and design of educational assessment. Washington, DC: National Academy Press.