In addition, students distinguish between characteristics of living organisms and nonliving objects, compare lifelong needs of plants and animals, understand how living organisms depend on their environments, and identify functions of parts of plants and animals. Science is a way of learning about the natural world. Students should know how science has built a vast body of changing and increasing knowledge described by physical, mathematical, and conceptual models, and also should know that science may not answer all questions. A system is a collection of cycles, structures, and processes that interact. Students should understand a whole in terms of its components and how these components relate to each other and to the whole.
All systems have basic properties that can be described in terms of space, time, energy, and matter.
Change and constancy occur in systems and can be observed and measured as patterns. These patterns help to predict what will happen next and can change over time. Investigations are used to learn about the natural world. Students should understand that certain types of questions can be answered by investigations, and that methods, models, and conclusions built from these investigations change as new observations are made. Models of objects and events are tools for understanding the natural world and can show how systems work.