As outlined in the NRC’s Framework for the Next Generation Standards:
Scientists construct mental and conceptual models of phenomena. Mental models are internal, personal, idiosyncratic, incomplete, unstable, and essentially functional. They serve the purpose of being a tool for thinking with, making predictions, and making sense of experience. Conceptual models are, in contrast, explicit representations that are in some ways analogous to the phenomena they represent.
Conceptual models are in some senses the external articulation of the mental model that scientists hold and are strongly interrelated with mental models. Building an understanding of models and their role in science helps students to construct and revise mental models of phenomena. Better mental models, in turn, lead to a deeper understanding of science and enhanced scientific reasoning.
Scientists use models to represent their current understanding of a system (or parts of a system) under study, to aid in the development of questions and explanations, and to communicate ideas to others. Modeling can begin in the earliest grades, with students’ models progressing from concrete “pictures” and/or physical scale models (e.g., a toy car) to more abstract representations of relevant relationships in later grades, such as a diagram representing forces on a particular object in a system. Students should be asked to use diagrams, maps, and other abstract models as tools that enable them to elaborate on their own ideas or findings and present them to others. Young students should be encouraged to devise pictorial and simple graphical representations of the findings of their investigations and to use these models in developing their explanations of what occurred.
More sophisticated types of models should increasingly be used across the grades, both in instruction and curriculum materials, as students progress through their science education. Curricula will need to stress the role of models explicitly and provide students with modeling tools so that students come to value this core practice and develop a level of facility in constructing and applying appropriate models.