This dimension focuses on important practices used by scientists and engineers, such as modeling, developing explanations or solutions, and engaging in argumentation. For example, all of the disciplines of science share a commitment to data and evidence as the foundation for developing claims about the world. As they carry out investigations and revise or extend their explanations, scientists examine, review, and evaluate their own knowledge and ideas and critique those of others through a process of argumentation. These practices have too often been underemphasized in K-12 science education.

Engaging in the full range of scientific practices helps students understand how scientific knowledge develops and gives them an appreciation of the wide range of approaches that are used to investigate, model, and explain the world. Similarly, engaging in the practices of engineering helps students understand the work of engineers and the links between engineering and science.

The full report describes these eight practices, articulating the major competencies that students should have by the end of 12th grade and outlining how student competence might progress across the grades.

The seven crosscutting concepts are key across science and engineering. They provide students with ways to connect knowledge from the various disciplines into a coherent and scientific view of the world. For example, the concept of “cause and effect: mechanism and explanation” includes the key understandings that events have causes, sometimes simple, sometimes multifaceted; that a major activity of science is investigating and explaining causal relationships and the mechanisms by which they are mediated; and that such mechanisms can then be tested across given contexts and used to predict and explain events in new contexts.

Students’ understanding of these crosscutting concepts should be reinforced by their repeated use in instruction across the disciplinary core ideas (see Dimension 3). For example, the concept of “cause and effect” could be discussed in the context of plant growth in a biology class and in the context of investigating the motion of objects in a physics class. Throughout their science and engineering education, students should be taught the crosscutting concepts in ways that illustrate their applicability across all the core ideas.

The framework includes core ideas for the physical sciences, life sciences, and earth and space sciences because these are the disciplines typically included in science education in K-12 schools. Engineering and technology are featured alongside these disciplines for two critical reasons: to reflect the importance of understanding the human-built world and to recognize the value of better integrating the teaching and learning of science, engineering, and technology.

The focus on a limited number of core ideas in science and engineering is designed to allow sufficient time for teachers and students to explore each idea in depth and thus with understanding. The full report provides detailed descriptions of each core idea, as well as descriptions of what aspects of each idea should be learned by the end of grades 2, 5, 8 and 12. Establishing limits for what is to be learned about each core idea for each grade band clarifies the most important ideas that students should learn.