1. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Table of Contents Measurements and Calculations Section 1 Scientific Method Section 2 Units of Measure Section 3 Using Scientific Measurements Chapter 2

2. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Scientific Method The scientific method is a logical approach to solving problems by observing and collecting data, formulating hypotheses, testing hypotheses, and formulating theories that are supported by data. Section 1 Scientific Method Chapter 2

3. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Observing and Collecting Data Observing is the use of the senses to obtain information. data may be qualitative (descriptive) quantitative (numerical) A system is a specific portion of matter in a given region of space that has been selected for study during an experiment or observation. Section 1 Scientific Method Chapter 2

4. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Formulating Hypotheses As scientists examine data, they find relationships and patterns, and make generalizations based on the data. Scientists try to explain generalizations about the data by formulating hypotheses. A hypothesis is a proposed explanation for what is observed; it must be testable. Section 1 Scientific Method Chapter 2

5. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Testing Hypotheses Testing a hypothesis requires experimentation that provides data to support or refute a hypothesis or theory. An experiment can test the effect of one variable on another. An experiment must be repeatable. Section 1 Scientific Method Chapter 2

6. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Testing Hypotheses Data is collected during experiments. The data is then organized and analyzed. If the data from the experiment does not support the hypothesis, it must be rejected and changed. The new or refined hypothesis is then subjected to further experimental testing.

7. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Theorizing Once a hypothesis successfully passes many experimental tests and can explain a large body of experimental facts, it becomes known as a theory. A theory is a broad generalization that explains a body of facts or phenomena. example: atomic theory A model in science is more than a physical object; it is often an explanation of how phenomena occur and how data or events are related. visual, verbal, or mathematical example: atomic model of matter Section 1 Scientific Method Chapter 2

8. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Scientific Method Section 1 Scientific Method Chapter 2

9. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Scientific Method Experimentation and explanation are closely related. The scientist performs a number of experiments and observes a regularity. The scientist then tries to explain the regularity by a hypothesis. The results of these experiments may agree with the hypothesis or they may not. If these and further experiments agree with the hypothesis, the hypothesis becomes a theory. If any experiment does not agree with the hypothesis, the hypothesis must be changed (assuming there is no flaw in the experiment). Of course, even if the explanation becomes a theory, it may someday need to be modified if subsequent experiments make this necessary.