The Scientific Method
Steps to the Scientific Method
(PRHEAD)
• Problem State the problem
• Research
• Hypothesis form a hypothesis
• Experiment design & conduct experiment
• Analyze Collected Data
• Draw Conclusion support or reject
hypothesis
P-Problem  State the Problem
• Gives you a reason for doing
the experiment
• This question MUST be
testable/measurable
• Ex: Which car oil will allow
my car to get the best gas
mileage?
Process It…Testable or Not?
Do cats make better pets than
dogs?
Process It…Testable or Not?
How do different types of
movement/activity affect human
heart rate?
Process It…Which is testable?
A. Which is the tastiest soda?
B. How many people will choose Dr.
Pepper over Coke?
R-Research
• In order to make an
educated guess
(hypothesis), you need to
find out more information
about the problem you
are trying to solve.
• Ex: research various oils
and their properties.
H-Hypothesis  form a hypothesis
• A hypothesis is an educated
guess about the solution to your
problem based on your
research.
• This is done with an “if / then”
statement. .
• Ex: If I use Havoline car oil then
my Lamborghini Diablo will get
better gas mileage.
Hypothesis MUST be:
1. Testable/ Fact-based-“Dr. Pepper is the
tastiest soda” is not fact-based, it’s based
on opinion, and therefore can not be a
hypothesis.
2. A sentence, not a question!!
Process It…Testable or Not?
If I use Havoline car oil then it
will be better than Mobile
Oil.
Process It…Testable or Not?
•If I use Havoline car oil then
my Lamborghini Diablo will
get better gas mileage.
E-Experiment  Design and
conduct experiment
• This is done to test the hypothesis.
• Design an experiment that will
provide data to support or reject
your hypothesis.
– Ex: Test four different car oils found
during research
Parts of an Experiment
• Independent Variable – The part of an experiment
that you change.
• EX: car oil
• Dependent Variable- What you are
recording/observing. It changes according to how
the independent variable changes
• Ex: gas mileage
– ONLY test one variable at a time!!!!!!!!!!
Parts of an Experiment
• Constant variables- quantities that remain
constant (the same) aka “controlled
variables”
• Ex: same car, same road
• Control group- what is used to COMPARE
the results to. It is the variable in which no
independent variable has been applied.
• Ex: test run with the original brand of oil in
the car
A-Analyze Collected Data
• Observations are recorded
facts about what you see
during the experiment.
–Graph: IV’s go on the x-axis
DV’s go on y-axis
D-Draw Conclusion  Support
or reject hypothesis
• This is a brief statement about the results
of the experiment.
• In the conclusion state if the hypothesis
was correct (supported) or incorrect
(rejected).
• Claim, evidence, reasoning
•TYPES OF DATA
Observation or Inference
Observation- See with own eyes
(ex; the apple is red, it is raining outside,
the window is 6ft long
Inference: What you think might
be true but not sure.
(ex: She is wiping her eyes, she is crying, He
has hair on his shirt, he owns a cat)
Types of Observations
• Qualitative – Results are
descriptive.
–ex: the litmus paper turned red
• Quantitative – Results are
numerical and have a unit.
–ex: 5 meters, 45 seconds
Accuracy vs Precision
• Accuracy- nearness to the actual value
• Precision- how close the data is together
Accuracy and precision: the target example
Precise, but not
accurate
Accuracy and precision: the target example
Accurate,
not precise
Accuracy and precision: the target example
Neither
accurate,
nor precise
Accuracy and precision: the target example
Accurate
and
precise
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