Scientific models are used to represent objects or systems in the natural world. There are three main types of scientific models: physical models, which resemble the actual object; mathematical models, which use equations and data; and conceptual models, which explain ideas through comparisons. Models allow scientists to study things that are too small, like cells, or too large, like the solar system. Models help illustrate scientific theories and build knowledge, though theories and models may change as new evidence is discovered. Scientific laws are formed when a theory's models consistently predict experimental results and summarize what is observed.

1. Scientific ModelsIntroduction to ScienceChapter 3.3

2. Objectives:Explain how models are used to represent the natural world.Identifythree types of scientific models.Describe theories and laws.Bellringer:To teach cardiopulmonary resuscitation (CPR), instructors often use a mannequin to model a human upper torso and head.Why do you think CPR is taught with a model instead of a real human?Would the class be as effective if a model were not used?

3. Types of ModelsModelA representation of an object or a system.Physical Modelslook like they thing they represent.For example, the model flower shown at right can be used to learn the parts of a real flower.

4. Mathematical Models Made up of mathematical equations and data.The weather map shown below is a mathematical model.Conceptual Models Systems of ideas or are based on making comparisons with familiar things to explain an idea.Explains the origin of the universe

5. Models are just the right sizeOften used to represent things that are very small or very large.Useful for studying cells and particles of matter that are too small to see with the unaided eye.Also useful for studying objects that are too large to see completelysuch as the Earth or the solar system.

6. Models build scientific knowledgeOften used to help illustrate and explain scientific theories.TheoryUnifying explanation for a broad range of hypotheses and observations that have been supported by testing.Theories and models can change as new observations are made.Charles Darwin’s Theory of Evolution1897 Model of AtomCurrent Model of Atom

7. Scientific Laws Formed when a theory and its models correctly predict the results of many different experiments.Law is defined as:A summary of many experimental results and observations.Laws are not the same as theories. Laws tell you only what happens, not why it happens.