Transcript Scientific Method - Instructional Resources

Scientific Method
Georgia CTAE Resource Network
Instructional Resource Office
To accompany curriculum for the Georgia Peach
State Career Pathways
April 2009, Kayla Calhoun & Dr. Frank Flanders
Objectives
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List steps of the scientific method
Explain how different variables are
used in an experiment
Contrast qualitative and quantitative
data
Demonstrate knowledge of scientific
method by performing an
experiment
What is the scientific method?
Principles and procedures for the
systematic pursuit of knowledge
involving recognition and
formulation of a problem, collection
of data through observation and
experiment, and formulation and
testing of hypotheses
Steps of the Scientific Method:
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6.
7.
Ask a Question
Make Observations & Research Topic
Form a Hypothesis
Design & Perform an Experiment
Collect & Analyze Data
Draw Conclusions
Make Recommendations
Step 1:
Ask a Question
Recognize a problem and develop a
question to be answered by
experimentation
Step 2:
Make Observations & Research Topic
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Make observations
Do background research on the
topic
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Find the best way to experiment
Don’t repeat past mistakes
Step 3:
Form a Hypothesis
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After researching the topic, develop
a hypothesis (an educated guess)
about the outcome of your
experiment
Basic format: “If I do this
(independent variable), then this
(dependent variable) will happen.”
Step 3 (continued):
Variables
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Independent variable (IV): the
experimenter changes this variable;
should only change one thing per
experiment
Dependent variable (DV): value depends
on the independent variable; its measure
determines if hypothesis was correct or
incorrect
All other conditions should remain
constant in all trials so that any changes
to the DV can be attributed to variation in
the IV
Step 4:
Design & Perform an Experiment
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Procedure should be clear and easy
to reproduce by others
Experimental group: independent
variable is altered
Control group: standard of
comparison; “no treatment” group
Only one factor is changed at a time
in the experimental group, keeping
all other conditions constant.
Step 5:
Collect & Analyze Data
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Collect measurements and analyze data
Procedure may be modified
Qualitative data relies on the senses and
reveals changes in behavior
Quantitative data relies on measurable
facts and figures
Repeat experiment a few times to
maximize accuracy of results.
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Each replication is referred to as a trial.
Step 6:
Draw Conclusions
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Based on analysis of results, accept
or reject the hypothesis
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Accept: test it again using a different
variable.
Reject: form a new hypothesis and go
through the process again.
Step 7:
Make Recommendations
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Recommend further
experimentation and possible
improvements to the procedure.
Consistent results may lead to…
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Theory: uses many experimental
observations, can be applied to new
situations, can be modified if new
data appears; cannot be proven,
only disproven
Law: confirmed in every
experiment, creates true predictions
for different situations, uniform, and
universal
Pasteur’s Spontaneous Generation
Experiment
The following slides explain how
Louis Pasteur used the steps of the
scientific method to disprove the
theory of spontaneous generation.
Pasteur’s Spontaneous Generation
Experiment
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Question: Can a nonliving substance
(broth) produce living cells (bacteria)?
Observation: bacteria appeared in
spoiled broth, and people thought the
broth became bacteria, or produced it
Hypothesis: If cells (bacteria) arise
from nonliving substances, they will
appear in sterile broth.
Pasteur’s Spontaneous Generation
Experiment
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Experiment:
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Pasteur prepared a nutrient broth and exposed
it to bacteria, contaminating it.
He placed equal amounts of the broth into two
long-necked flasks. One had a straight neck,
and the other had a swan neck.
Pasteur’s Spontaneous Generation
Experiment
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Experiment:
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He boiled both flasks of broth to kill any
existing bacteria (sterilization) and then left
them at room temperature.
Pasteur’s Spontaneous Generation
Experiment
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Observation: Bacteria
appeared only in the
control flask with the
straight neck; dust and
condensed water
accumulated in the swan
necked flask.
 Analysis: Dust carrying
bacteria was able to fall
into the straight-necked
flask, but gravity forced it
to stop in the neck of the
swan-necked flask.
 Bacteria only
contaminated the flask
in which dust was able
to enter.
Pasteur’s Spontaneous Generation
Experiment
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Conclusions:
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The shape of the flask affected the
amount of bacteria in the broth;
therefore, the broth did not produce
the bacteria.
The hypothesis of spontaneous
generation is rejected.
Summary
Steps of the Scientific Method:
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Ask a Question
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Make Observations & Research Topic
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Form a Hypothesis
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Design & Perform an Experiment
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Collect & Analyze Data
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Draw Conclusions
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Make Recommendations