Within the Next Generation Science Standards (NGSS), there are three distinct and equally important dimensions to learning science: Science and Engineering Practices, Crosscutting Concepts, and Disciplinary Core Ideas.
The first dimension, Science and Engineering Practices, describes what scientists do to investigate the natural world and what engineers do to design and build systems. The second dimension, Crosscutting Concepts, helps students explore connections across the four domains of science, including Physical Science, Life Science, Earth and Space Science, and Engineering Design. The third dimension, Disciplinary Core Ideas, includes the key ideas in science that have broad importance within or across multiple science or engineering disciplines. These dimensions are combined to form each standard—or performance expectation—and each dimension works with the other two to help students build a cohesive understanding of science over time. The Science Standards are not a set of daily standards, but a set of expectations for what students should be able to do by the end of instruction.