System and System Models

Developing and using models is identified in the framework as an important practice of science. The concept of models is so important to both science and engineering that systems and system models are also identified as a crosscutting concept. Scientists and engineers use models to represent systems that are very large, very small, very complex, or abstract. Models can be both descriptive and predictive. Some of the many types of models that are used in science and engineering include conceptual models such as drawings and diagrams (Fig. 1), maps (Fig 2.), three-dimensional structures, physical scale models, mathematical formulas, analogies, computer simulations, and mental models.

In creating and using models, it is important to define the system being described. A system is a group of objects or components that, together, form a whole. Systems are made up of components and have defined boundaries. Systems can interact with other systems, or be components of larger, systems. In order to understand models, it is important to define the system and to understand the limitations of the model in representing the system.

The framework suggests that students can build an understanding of models and systems, starting with drawings, diagrams, and plans in the elementary grades. As students progress, their models should become more complex and explicit, indicating relationships and interactions between and within systems. Students should view models as tools for learning and understanding science and engineering concepts. In the classroom, instruction should guide students to create and present models using diagrams, words, and mathematical representations when appropriate.