1. Section 3: Scientific Methods
Scientists use scientific methods to systematically pose and test solutions to questions and assess the results of the tests. K
What I Know W
What I Want to Find Out L
What I Learned

2. Essential Questions What are the common steps of scientific methods?
What are the similarities and differences between qualitative data and quantitative data?
In an experiment, which variable is the independent variable, which is the dependent variable, and which are controls?
What is the difference between a scientific theory and a scientific law?
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Scientific Methods

3. Vocabulary Review New New systematic approach experiment
independent variable
dependent variable
control
conclusion
theory
scientific law
New
scientific method
qualitative data
quantitative data
hypothesis
Scientific Methods
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4. A Systematic Approach
The scientific method is a systematic approach used in scientific study, whether it is chemistry, physics, biology, or another science.
It is an organized process used by scientists to do research, and provides methods for scientists to verify the work of others.
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Scientific Methods

5. A Systematic Approach
The steps in a scientific method are repeated until a hypothesis is supported or discarded.
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Scientific Methods

6. A Systematic Approach
An observation is the act of gathering information.
Qualitative data is obtained through observations that describe color, smell, shape, or some other physical characteristic that is related to the five senses.
Quantitative data is obtained from numerical observations that describe how much, how little, how big or how fast.
Recall in section1, Scientists observed that there were CFCs in the atmosphere and that their levels were increasing.
A hypothesis is a tentative explanation for what has been observed.
Scientists hypothesized that CFCs, although stable, break down in the stratosphere due to interactions with ultraviolet radiation from the Sun, and that the chlorine produced by this interaction would break down ozone.
An experiment is a set of controlled observations that test the hypothesis.
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Scientific Methods

7. A Systematic Approach
A variable is a quantity or condition that can have more than one value.
An independent variable is the variable you plan to change.
The dependent variable is the variable that changes in value in response to a change in the independent variable.
If you were trying to determine if temperature affects bacterial growth, you would expose different petri dishes of the same bacteria to different temperatures.
Temperature is your independent variable.
Bacteria growth is your dependent variable.
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Scientific Methods

8. A Systematic Approach
A control is a standard for comparison in the experiment.
During clinical drug trials, physicians will use a double-blind study. They use two statistically identical groups of patients. One will receive the drug and one will receive a placebo. Neither patient or physician will know which group receives the drug.
The group receiving the placebo is the control group.
A conclusion is a judgment based on the information obtained from the experiment.
A hypothesis is never proven, only supported or discarded.
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Scientific Methods

9. Add link to concepts in motion animation from page 10 here.
Ozone Depletion (Analyzing Data)
Concepts in Motion
FPO
Add link to concepts in motion animation from page 10 here.
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Scientific Methods

10. Theory and Scientific Law
A theory is an explanation that has been repeatedly supported by many experiments.
A theory states a broad principle of nature that has been supported over time by repeated testing.
Theories are successful if they can be used to make predictions that are true.
A scientific law is a relationship in nature that is supported by many experiments, and no exceptions to these relationships are found.
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Scientific Methods

11. Review Essential Questions Vocabulary
What are the common steps of scientific methods?
What are the similarities and differences between qualitative data and quantitative data?
In an experiment, which variable is the independent variable, which is the dependent variable, and which are controls?
What is the difference between a scientific theory and a scientific law?
Vocabulary
scientific method
qualitative data
quantitative data
hypothesis
experiment
independent variable
dependent variable
control
conclusion
theory
scientific law
Copyright © McGraw-Hill Education
Scientific Methods