The scientific method
The scientific method is a logical approach to solving problems that uses observation and
experimentation. It involves observing and asking questions, formulating hypotheses,
testing hypotheses, and drawing conclusions.
Observations → Formulating hypotheses → Testing hypotheses →Drawing conclusions
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Observations
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Observation – the use of the senses to obtain information. Observations
lead to questions which can be answered through experimentation.
Inference - An inference is a logical interpretation of an observation based
on prior knowledge or experience.
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Hypothesis
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A hypothesis is a proposed explanation for an observation or question.
A hypothesis must be testable.
A good hypothesis explains an observation and predicts the outcome of an
experiment.
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Testing the hypothesis
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An experiment is a step by step procedure that can be used to test a
hypothesis.
A traditional experiment tests the effect of one variable on another, while
keeping all other variables constant.
An experiment must be repeatable.
Preparing the experiment
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Identify the independent variable (the factor that the tester will change or
manipulate).
Identify the dependent variable (the factor that changes when the
independent variable is changed).
Identify variables that must be kept constant (the factors that will remain
unchanged during the experiment).
Identify the control group if one will be used. The control group is the group
in an experiment that does not receive the experimental treatment. It is
used for comparison.
Develop a step by step procedure to carry out the experiment that allows
you to collect sufficient relevant data.
Determine what materials and equipment is necessary for the experiment.
Collecting and organizing data
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During the experiment, record all relevant data. The data obtained may be:
 Qualitative – descriptive
Quantitative – numerical
Record quantitative raw data (data that was measured not calculated) in a
data table. Label the units of each measurement.
A graph can be used to organize the data collected.
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Drawing conclusions
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Draw conclusions based on data from experiment.
Reject, modify, or accept the hypothesis.
Experiment further to prove or disprove proposed explanations.
After performing many experiments, a scientist may note some regularity in
the results and express this regularity as a scientific law.
A theory may eventually be developed to explain a large body of
experimental facts and laws.
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Scientific Laws
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A scientific law is a general statement based on the observed behavior of
matter.
A scientific law does not attempt to explain why the observed behavior
occurs.
Scientific laws result from many observations and experiments.
For example, the law of conservation of matter states that there is no
detectable change in the total quantity of matter during a chemical reaction
or a physical change.
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Scientific Theories
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A theory is a broad and extensively tested explanation of observations and
scientific laws.
One or more well-established hypotheses may become part of a theory. So,
a theory provides a broader and deeper explanation of observations and laws
than a hypothesis.
Theories are considered successful if they can predict the results of new
experiments.
For example: Dalton’s atomic theory proposes that all matter is composed of
small, indestructible particles called atoms. This theory explains the law of
conservation of matter as well as other laws
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If a hypothesis, law, or theory is inconsistent with the findings of an experiment, it must
be discarded or modified.