1. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Scientific Models 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? Explain your answer. Chapter 1

2. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Scientific Models Objectives Explain how models are used to represent the natural world. Identify three types of scientific models. Describe theories and laws. Chapter 1

3. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Scientific Models Types of Scientific Models A representation of an object or a system is called a model. Chapter 1 Physical Models look 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. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Scientific Models Demonstrate both a solar eclipse and a lunar eclipse using a large ball, a small ball and flashlight. Chapter 1

5. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Scientific Models Types of Scientific Models, continued Mathematical Models are made up of mathematical equations and data. The weather map shown below is a mathematical model. Chapter 1

6. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Scientific Models Types of Scientific Models, continued Conceptual Models are systems of ideas or are based on making comparisons with familiar things to explain an idea. The big bang theory explains the origin of the universe. This theory is an example of a conceptual model. Chapter 1

7. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu CONCEPTUAL MODEL OF AN ATOM

8. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 1 Section 3 Scientific Models The model of the atom has changed many times. Atoms were once imagined as tiny balls. We can use sour ball candies to represent them. Later, the atom was imagined to look like a chocolate chip cookie (with negative charges stuck in a positive substance). In your study of atomic structure you will learn that more models have been proposed. We use edible models to represent them.

9. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 1Section 3 Scientific Models Oreo cookies can be used to model the phases of the moon. Scrape (or eat) the cream from the middle of each cookie.

10. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Scientific Models Models Are Just the Right Size Models are often used to represent things that are very small or very large. Models are useful for studying cells and particles of matter that are too small to see with the unaided eye. Models are also useful for studying objects that are too large to see completely, such as the Earth or the solar system. Chapter 1

11. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Scientific Models Models Build Scientific Knowledge Models are often used to help illustrate and explain scientific theories. In science, a theory is a unifying 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. Chapter 1

12. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu A theory is an explanation for many hypotheses and observations. A theory explains an observation you have made and can predict what might happen in the future.

13. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Scientific Models Models Build Scientific Knowledge, continued Scientific Laws When a theory and its models correctly predict the results of many different experiments, a scientific law could be formed. In science, a law is a summary of many experimental results and observations. A law tells you how things work. Laws are not the same as theories. Laws tell you only what happens, not why it happens. Chapter 1