Transcript Experimental Design

Experimental Design
Student Activity
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Divide into groups of 3.
Using the shapes written on the boardArrange the shapes on a piece of paper.
Design and write a procedure so that
other groups will arrange shapes identical
to the way your group did.
The Scientific Method:
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5.
State the Problem
Form a hypothesis
Set up a controlled experiment
Record and analyze results.
Draw a conclusion.
Designing an Experiment
State the Problem
Analyze Results
Form a Hypothesis
Draw a Conclusion
Set Up a Controlled Experiment
Publish Results
Record Results
Go to
Section:
Hypothesis
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educated guess
Example of an Educated Guess
Independent variable:
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the variable which is manipulated
also called the manipulated variable
this is what you change
Example: Amount of water
Dependent variable
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also called the responding variable
Changes because of what you did to it
(independent)
This is the outcome
Example: Growth of the plant
Control variables
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all other variables are kept the same in
order to be sure which affected the
outcome
Example:
Amount of sunlight
Temperature
Others???
control/control set-up
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used to compare results to
In testing if light effects the growth of a
plant: control= no light
Spontaneous Generation
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poof-it just occurs there
Keep in mind what Spontaneous
generation is when discussing the
experiments of the following scientists!
Francesco Redi Experiment on Spontaneous Generation
OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat.
HYPOTHESIS: Flies produce maggots.
PROCEDURE
Uncovered jars
Controlled Variables:
jars, type of meat,
location, temperature,
time
Covered jars
CONCLUSION: Maggots form
only when flies
come
in
Several
days
pass
Independent Variables:contact with
meat.
gauze covering that
keeps flies away from Spontaneous generation
meat
of maggots did not
Dependent
Variable:
Maggots appear
occur.
No maggots appear
whether maggots
appear
Anton van Leeuwenhoek
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Description: prepared
lenses to magnify,
found animalcules or
tiny animals
Conclusion: Were
animalcules alive or
how did they come to
exist?
John Needham
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Description: See
Spallanzani’s
Experiment
He first did the
experimentSpallanzani repeated
Conclusion:
Spontaneous
generation occurred.
Lazzaro Spallanzani
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Description: thought
Needham did not heat
the flasks enough
Conclusion:
Flask is
open.
Spontaneous
generation did not
occur. Micro
organisms not found
in sealed flask after
Flask is
heating.
sealed.
Gravy is teeming
with
microorganisms.
Gravy is free of
microorganisms.
Louis Pasteur
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Conclusion: Hypothesis of spontaneous
generation not correct!
Pasteurization
Broth is free of
microorganisms
Broth is boiled. for a year.
Broth is
Curved neck teeming with
is removed. microorganisms
Theory
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Dictionary definition: speculation
People often use the word theory when they are
really referring to a hypothesis.
Example: I have a theory about why the
washing machine does not work.
Scientific definition: well tested explanation that
unifies a broad range of observations.
Example: Theory of Plate tectonics, the theory
of Evolution, and the Cell Theory