Section 2: Scientific Methods

Scientists use scientific methods to systematically pose and test solutions to questions and assess the results of the tests.

KWhat I Know

WWhat I Want to Find Out

LWhat I Learned

• 2(C) Know that scientific theories are based on natural and physical phenomena and are capable of being tested by multiple independent researchers. Unlike hypotheses, scientific theories are well– established and highly–reliable explanations, but may be subject to change as new areas of science and new technologies are developed.

• 2(B) Know that scientific hypotheses are tentative and testable statements that must be capable of being supported or not supported by observational evidence. Hypotheses of durable explanatory power which have been tested over a wide variety of conditions are incorporated into theories.

• 2(D) Distinguish between scientific hypotheses and scientific theories.

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• 2(E) Plan and implement investigative procedures, including asking questions, formulating testable hypotheses, and selecting equipment and technology, including graphing calculators, computers and probes, sufficient scientific glassware such as beakers, Erlenmeyer flasks, pipettes, graduated cylinders, volumetric flasks, safety goggles, and burettes, electronic balances, and an adequate supply of consumable chemicals

• 2(H) Organize, analyze, evaluate, make inferences, and predict trends from data.

• 2(I) Communicate valid conclusions supported by the data through methods such as lab reports, labeled drawings, graphs, journals, summaries, oral reports, and technology–based reports.

• 3(A) In all fields of science, analyze, evaluate, and critique scientific explanations by using empirical evidence, logical reasoning, and experimental and observational testing, including examining all sides of scientific evidence of those scientific explanations, so as to encourage critical thinking by the student.

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Essential Questions

• What are the common steps of scientific methods?

• What are the variables and the controls in an experiment?

• What is the difference between a scientific theory and a scientific law?

Scientific MethodsCopyright © McGraw-Hill Education

Review• systematic approach

New• experiment • independent variable• dependent variable• control• conclusion• scientific theory• scientific law

Scientific MethodsCopyright © McGraw-Hill Education

Vocabulary

New• scientific method• qualitative data• quantitative data• hypothesis

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. The steps in a scientific method are repeated until a hypothesis is supported or discarded.

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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.

Scientific MethodsCopyright © McGraw-Hill Education

Qualitative vs. Quantitative

Scientific Method5 Steps:

1. Problem2. Hypothesis3. Experiment4. Observations & Data5. Conclusion

1) Problem -

“What’s wrong?”

2) Hypothesis -“Educated Guess”

predict what will happenBased on prior knowledge

3) Experiment -Test your hypothesis

a) Control Group – stays the same, used for comparison

b) Variable Group – what you manipulate that changes

1. Independent Variable – what the experimenter (I) changes.

2. Dependent Variable – what is observed/measured.

The dependent variable depends on the independent variable

The independent variable is what I change!!!

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.

3. Control Variables – all other variables that are kept constant.

Remember, a good experiment only has two variables that change (independent and dependent). All the rest of the variables must be the same.

• 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.

when graphing…

4) Observations &

Data collection

5) Conclusion -

- Based on observations

Might support hypothesis!

Ozone Depletion (Analyzing Data)

Concepts in Motion

FPOAdd link to concepts in motion animation from page 10 here.

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Theory and Scientific Law

A scientific 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.

Scientific MethodsCopyright © McGraw-Hill Education

Scientific MethodsCopyright © McGraw-Hill Education

Review

Essential Questions•What are the common steps of scientific methods?

•What are the variables and the controls in an experiment?

•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• scientific theory• scientific law