We also introduce a fourth core idea: PS4: Waves and Their Applications in Technologies for Information Transfer—which introduces students to the ways in which advances in the physical sciences during the 20th century underlie all sophisticated technologies available today. This idea is included in recognition of the fact that organizing science instruction around disciplinary core ideas tends to leave out the applications of those ideas. The committee included this fourth idea to stress the interplay of physical science and technology, as well as to expand students’ understanding of light and sound as mechanisms of both energy transfer (see LS3) and transfer of information between objects that are not in contact. Modern communication, information, and imaging technologies are applications of scientific understandings of light and sound and their interactions with matter. They are pervasive in our lives today and are also critical tools without which much of modern science could not be done. See Box 5-1 for a summary of these four core ideas and their components.
The first three physical science core ideas answer two fundamental questions—“What is everything made of?” and “Why do things happen?”—that are not unlike questions that students themselves might ask. These core ideas can be applied to explain and predict a wide variety of phenomena that occur in people’s everyday lives, such as the evaporation of a puddle of water, the transmission of sound, the digital storage and transmission of information, the tarnishing of metals, and photosynthesis. And because such explanations and predictions rely on a basic understanding of matter and energy, students’ abilities to conceive of the interactions of matter and energy are central to their science education.
The historical division between the two subjects of physics and chemistry is transcended in modern science, as the same physical principles are seen to apply from subatomic scales to the scale of the universe itself. For this reason we have chosen to present the two subjects together, thereby ensuring a more coherent approach to the core ideas across all grades. The designation of physical science courses at the high school level as either physics or chemistry is not precluded by our grouping of these disciplines; what is important is that all students are offered a course sequence that gives them the opportunity and support to learn about all these ideas and to recognize the connections between them.