Scientific
Method
What is the scientific
method?
 The scientific method is the basic method, guide, and
system, by which we originate, refine, extend, and
apply knowledge in all fields.
 An organized approach that characterizes science
How do we (scientists) answer questions
about the world?
The Scientific Method
Step 1: Ask a Question
 Who?
 What?
 When?
 Where?
 Why?
 How?
The answer needs to be something you can MEASURE.
Preferably a number.
Step 2: Background
Research
 Background research needed to formulate hypothesis.
 Background research from reliable source.
Step 3: Formulate a
Hypothesis
 Your hypothesis must be an
IF….THEN…..BECAUSE statement.
 It must contain an independent
dependent variable.
 Must be a testable statement.
variable and a
 The scientific method has 5 steps:
To help you remember the steps of the scientific
method, think of the word "POHEC".
1) State the
2) Make
Problem
Observations
3) Form a
Hypothesis
4) Do the
Experiment
5) Draw a
Conclusion.
Independent and
Dependent Variables
Independent Variable (IV)
Dependent Variable (DV)
The condition being studied
The condition being affected by the IV
Controlled by the researcher
Cannot be controlled by the researcher
Independent Variable Example
Dependent Variable Example
Cause
Effect
Before
After
Input
Output
What you do
What happens
Step 4: Test Your Hypothesis
Through Experimentation
 Use repeated trials
 Good experiments have 2 groups
 Control Group
 Independent variable eliminated or not present
 Experimental Group
 Independent variable being tested
Step 5: Analyze Data and
Draw Conclusions
 What does the data from your experiment tell you?
 How to analyze data:
 Charts
 Graphs
 Equations
 Does it support your hypothesis?
 Do you need to reject your hypothesis?
Step 6: Report Your
Results
 If data does not support your hypothesis, revise it and
retest.
 If your data supports your hypothesis:
 Repeat the experiment several times.
 Publish in peer reviewed publications.
 Brag about it! Yay!
Activity
 Explain how you would test one of the following
questions using the scientific method:
 Are male manatees always larger than female
manatees?
 Does caffeine make people hyper?
 Does studying more help students to do better on tests?
 Is penicillin a more effective antibiotic against
than tetracycline?
E. coli
Forming a Hypothesis
Reminder:
 Your hypothesis must be an IF….THEN…..BECAUSE
statement.
 It must contain an independent variable and a dependent
variable.
 Must be a testable statement.
Independent Variable (IV)
Dependent Variable (DV)
The condition being studied
The condition being affected by the IV
Controlled by the researcher
Cannot be controlled by the researcher
Independent and
Dependent Variables
 The variable which depends on the other variable is
the: Dependent
Variable
The variable being tested in a scientific experiment
 The other variable which doesn’t depend on anything
is the: Independent
Variable
The variable that is changed to test the effects
Independent and
Dependent Variables
Independent Variable
Dependent Variable
Cell phone minutes used
Cell phone bill
Amount of gas you have
How far you drive
Number of assignments you turn in
Your 9 week grade
Number of hours you work
How much money you earn
Miles over the speed limit
Cost of a speeding ticket
How fast you drive
Time it takes to drives somwhere
Who scores the most points in football
Result of a football game
Hypothesis – “IF”
Statement
Begins with “IF” statement
 The “If ’’ Statement

Start your sentence with “if ”

Write down one of your variables

Add a connecting statement
 Is related to
 Is affected by
 Causes
 Write down the other variable

Ex. IF water is related to plant growth,…..
Hypothesis – “THEN”
Statement
The “Then”Statement
 Write the word THEN
 Make a comment about the relationship between the
two variables
 EX. THEN the more you water plants, the bigger they
will grow
Hypothesis - Because
 Last part of hypothesis is BECAUSE
 WHY based on REASON.
 Add to end of hypothesis.
 Ex. IF water is related to plant growth, THEN the more
you water plants, the bigger they will grow BECAUSE
water is necessary for plants to undergo photosynthesis.
Hypothesis - Summary
If __IV___ (connecting statement)__DV___, then
(comment about how the variables relate),
because….(why based on reason).
Connecting statements:
 Is related to
 Is affected by
 Causes
Examples
 IF skin cancer is related to ultraviolet light, THEN
people with a high exposure to UV light will have a
higher frequency of skin cancer because UV radiation
causes DNA mutations.
 IF the frequency of winning the lottery is related to
the frequency of buying lottery tickets, THEN the
more lottery tickets that you buy the better your
chance of winning because of probability.
Hypothesis Writing
Practice!
1. Chocolate may cause pimples.
2. Salt in soil may affect plant growth.
3. Bacterial growth may be affected by temperature.
4. Temperature may cause leaves to change color.