The Scientific Method
8-19-15
 I CAN explain the steps of the scientific
method and identify variables involved
in experimental study.
Introduction to the Scientific Process
The Scientific Method is a
logical, systematic approach to
solving a scientific problem.
Overview of the Scientific Process
Identify a
problem
Gather
Information
Formulate a
hypothesis
Analyze Data
Record and
Organize Data
Design an
Experiment
Draw
Conclusions
Conclusions can lead to revising the existing
hypothesis or developing a new hypothesis.
Step 1: Identify a Problem
 Observe the world around you.
• Using observations, identify a problem you would
like to solve.
• This is a question you DO NOT know the answer to and
can’t look up and must be testable.
 “Why” and “What would happen if…” are good
beginnings of scientific questions.
Step 2: Gather Information
 Use references to do background research.
 (Do not need to reinvent the wheel!)
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Books
Journals
Magazines
Internet
TV
Videos
Interview Experts
Step 3A: Formulate a Hypothesis
Possible answer to a question that can
be tested.
Based on observations and knowledge.
“If” “Then” or “Because” statement.
Step 3B: Formulate a Null Hypothesis
It’s very possible that a hypothesis will
NOT be supported by the research.
An experiment also has a NULL
HYPOSTHESIS – this is a statement that
says there is NO RELATIONSHIP
BETWEEN THE VARIABLES being
studied in the experiment.
Step 4: Develop an Experiment
An EXPERIMENT is a procedure designed to TEST
A HYPOTHESIS.
•Organized, well thought out, step by step process.
Can take place in a LABORATORY or in the FIELD.
Involves a number of VARIABLES – factors that can
change the outcome of the experiment.
Variables: Manipulated Variable
 The MANIPULATED VARIABLE is the factor that
the experimenter CHANGES to observe its
effect(s).
 Sometimes called the Independent
Variable.
Variables: Responding Variable
Changes in response to the
manipulated variable.
Is measured in the experiment.
Sometime called the Dependent
Variable.
Variables: Constant
All the factors in the experiments
that are kept the same are known as
CONSTANTS.
Everything except the manipulated
and responding variables.
Keeps the experiment “fair”.
Variable: Control Group
The normal condition that you
compare the responding variable to.
Allows the experimenter to decide
the effects of the manipulated
variable.
Step 5: Record and Organize Data
Write down all observations and
measurements.
NEVER destroy data!
Use tables/graphs/charts to organize your
data.
Label Everything including manipulated
and responding variables.
Step 6: Analyze Data
EXAMINE the data collected.
Does it SUPPORT the hypothesis?
YES
NO
1. Repeat experiment.
1. Repeat experiment.
2. Have others conduct same
experiment.
2. Review/discard
hypothesis.
Exit Slip
 A student in Mrs. Wright’s agriculture class wants to know if
Miracle Grow fertilizer will help tomato plants grow larger
than a generic brand from Wal-Mart. The student plants
three plots of 20 plants each. One receives Miracle Grow,
one the generic brand and the third no fertilizer. The height
of the plants is measured and recorded every three days for
6 weeks.
1. What would be a valid hypothesis for this experiment?
2. What would be a null hypothesis for this experiment?
3. Why did the third group of plants get no fertilizer at all?
4. What are some controls in this experiment?