2. Scientific Models Chapter 1 Section 3

3. I can describe how a model is used to represent the natural world. I can identify three types of scientific models. I can describe a theory. I can describe a law.

4. Scientific Models A representation of an object of system is called a model or prototype Scientific models are based upon experiments that tell us how one variable relates to another There are three types of scientific models Scientists are constantly trying to create better models to explain their theories

5. Physical Model  Can be looked at, touched, and we can take measurements from it. Example – a scale model  Some look like the thing they are modeling  Some act somewhat like the thing they model

6. Mathematical Models  Made up of mathematical equations and data  Some mathematical models are simple such as force = mass x acceleration  Others are so complex that only computers can handle them. http://www.shodor.org/featured/DiseaseModel/applet/

7. Conceptual Model  Used to describe how something works  Some are a system of ideas  Others are based on making comparisons with familiar things to help illustrate or explain an idea Example: Big Bang Theory

8. Uses of Models  Represent things that are too small to see with the naked eye  Represent things that are too large to see with human eye  Help illustrate and explain scientific theories  Models are changed or replaced as theories change

9. Models Build Scientific Knowledge  A theory is a unifying explanation for a broad range of hypothesis and observations that have been supported by testing  Models can be used to help support a theory or show it to be wrong  Remember models change as theories change  If something holds true through many experimental results and observations it becomes a scientific law.  A law tells you what happens, not why it happens  A law holds true every time you perform the experiment

10. Scientific Law vs. Scientific Theory Law of Gravity A theory tries to explain why or how something happens. A law states what happens. Theory of Gravity Atomic Theory Collision Theory of Reactions

11. Scientific Law Laws of nature never change. Charles’s Law V 1 V 2 T 1 T 2 =

12. Theory vs. Natural Law Scientific theoryNatural law Experiment Hypothesis analyze additional data analyze initial observations

13. Make observation Ask question Develop hypothesis Develop hypothesis Test hypothesis with an experiment Test hypothesis with an experiment Analyze data and draw conclusions Analyze data and draw conclusions Hypothesis IS supported Hypothesis IS supported Hypothesis is NOT supported Hypothesis is NOT supported Develop theory Develop theory Test hypothesis with further experiments Test hypothesis with further experiments Revise hypothesis Revise hypothesis Wysession, Frank, Yancopoulos, Physical Science Concepts in Action, 2004, page 8 Scientific Method

14. Results confirmed by other scientists – theory validate theory. Data do not support hypothesis hypothesis – revise or reject hypothesis Stages In The Scientific Method OBSERVING collecting data measuring experimenting communicating TESTING predicting experimenting communicating collecting data measuring THEORIZING constructing models predicting communicating PUBLISH RESULTS communicating FORMULATING HYPOTHESES organizing and analyzing data classifying inferring predicting communicating

15. Theories and Laws The Earth is flat… Speeding kills (Audubon, Germany); theory No explanation of why…but the theory is if you drive at 120 mph and crash, an ambulance won’t need to be called (only next of kin). seat belts save lives… LAW LAW: 65 mph and wear seat belt

16. Why Dinosaurs Disappeared Dinosaurs MeteorEarth Dust Cloud Moon is formed Ice Age - Glaciers RIP Meteor Crater Sun blocked Evidence… A theory…

17. Scientific Method and Law

18. I can describe how a model is used to represent the natural world. I can identify three types of scientific models. I can describe a theory. I can describe a law.

21. Scientific Tool For Today Today you will learn how to accurately measure length Measured in meters (usually in centimeters) Measured with a ruler, meter stick, or measuring tape