The Scientific Method
Unit 1: The Scientific Method
Chapter 1-1 & 1-2
Standards

Investigation & Experimentation
– 1a) Select and use appropriate tools and technology
(such as computer-linked probes, spreadsheets, and
graphing calculators) to perform tests, collect data,
analyze relationships, and display data.
– 1b) Identify and communicate sources of unavoidable
experimental error.
– 1c) Identify possible reasons for inconsistent results,
such as sources of error or uncontrolled conditions.
– 1d) Formulate explanations by using logic and
evidence.
– 1f) Distinguish between hypothesis and theory as
scientific terms.
– 1k) Recognize the cumulative nature of scientific
evidence
What is Science?

Science is method of thinking about
the natural world.
 Biology is the scientific study of life.
Scientific Method

The scientific method is a problemsolving procedure scientists use to
seek answers to questions.
THE SCIENTIFIC METHOD
PROBLEM
HYPOTHESIS
EXPERIMENT
REPEAT THE
WORK
RECORD DATA &
FORM A NEW
HYPOTHESIS
ANALYZE RESULTS
CONCLUSION
ACCEPT HYPOTHESIS
REJECT HYPOTHESIS
Scientific Method
1. Identify a Problem
2. Create a Hypothesis
3. Design and perform an
experiment.
4. Record Data and Analyze
5. State a Conclusion
6. Repeat the Work
1. Identify a Problem
 Observations
are descriptions
about the way something is or
the way things happen
 From
these observations, a
question is formed about why
or how
Example: Identify a problem

Barney observes:
– When I drink Coke, I burp a lot.

He asks Professor Frink:
– Why does Coke cause burping?
Example: Identify a problem

Professor Frink explains:
– You can do background research to
help you know more
• Look online about the physiology of burping
Wikipedia - not always 100% accurate, but a good
start for background information
carbon dioxide in drinks causes gas
pressure to build in the stomach
2. Create a Hypothesis

A Hypothesis is a prediction that
may provide an answer to the
question
– Must be testable
– Should be written in the form of an
“If…, then…” statement
Example: Create a Hypothesis
If
people drink Coke,
then they will burp more.
3. Controlled Experiment
 Test the
hypothesis
 Procedure—the steps followed
during an experiment
 Well designed experiments have
experimental group(s) & a
control group
Example: Experiment
Professor Frink wants to determine
if Coke will increase the frequency
of burping.
 He gives 10 volunteers (subjects)
from Springfield Coke and another
10 subjects water. All other
conditions are kept the same.

• All people are 20-30 years old
• All people are healthy.
• All people have to not eat or drink for 3
hours before the experiment.
Subject
 Control
Group: all variables are
kept the same (constant)
– Used as “normal” for comparison
 Experimental Group:
all the
same variables except the one
thing you are testing
 Variables: anything that can
influence the outcome of the
experiment
Example: Experiment
Control Group: people who drink
water only
 Experimental Group: people who
drink Coke
 Variables: age of subjects, health of
subjects, having food or drinks
before the experiment


Independent Variable: What you are
testing
– The variable that is changed

Dependent Variable: what is
measured or observed
– The variable that changes because of
the independent variable
Independent Variable: type of
beverage
 Dependent Variable average
number of burps

Control
Independent
Variable

The experimental group gets the
independent variable-Coke.
Independent
Variable

The control group gets the controlwater.
Control
4. Record Data & Analyze

Collect & record Data (information)
– Qualitative data: descriptions
– Quantitative data: numbers
• Data can be recorded in a table

Analyze the data by graphing it
– Bar graphs: show comparisons
– Line graphs: show changes over time
Example: Recording Data
Control
Group: Water
Experimental
Group: Coke
Average # of
Burps
2
Dependent Variable:
what you measure
6
Independent
Variable
Control
 Analyze
the Results: Bar Graph
Proper units
Title
Occurrence of Gas Expulsion for NonAverage
Number of Burps for Water vs. Coke
carbonated vs. Carbonated Beverages
7
# OF BURPS
6
5
4
3
2
1
0
WATER
Label
Type of Beverage
X-axis = Independent Variable
COKE
5. Conclusions
 The
results tell whether the
hypothesis was “accepted or
rejected”
Example: Conclusion
 Accept
or reject the
hypothesis?
– ACCEPT!
 Why?
– There were more burps
with Coke than with
water based on the
data and the results of
the graph.
6. Repeat the Work

When a hypothesis is supported by
data from additional investigations,
it is considered valid.

When a hypothesis is not supported,
it means that we need to go back
and ask new questions or identify
sources of error in the experiment.

Sources of error: things that may
effect the results of the experiment
– Sample Size: more subjects means
more accurate results
– Control all other variables but the one
you are testing
•
•
•
•
Length of experiment (hour vs. a day?)
Amount of variable (2 cokes vs. 1?)
Type of material (coke vs. pepsi?)
Other: light, temperature, age, health, male
vs. female, etc.
Hypothesis vs. Theory

Hypothesis: an educated guess that
may or may not be true
 Theory: a well-tested explanation
that unifies a broad range of
observations
– In science, theories are nearly facts
– Ex. Theory of Evolution,
Theory of Relativity,
Cell Theory
THE SCIENTIFIC METHOD
REPEAT THE
WORK
ACCEPT HYPOTHESIS
FORM A NEW
HYPOTHESIS
REJECT HYPOTHESIS
THE SCIENTIFIC METHOD
PROBLEM
HYPOTHESIS
EXPERIMENT
REPEAT THE
WORK
RECORD DATA &
FORM A NEW
HYPOTHESIS
ANALYZE RESULTS
CONCLUSION
ACCEPT HYPOTHESIS
REJECT HYPOTHESIS