Transcript experimental

SCIENCE
Defined as the use of evidence
to construct testable
explanations and predictions of
natural phenomena
SCIENCE, cont.
Some questions are outside the realm
of science because they deal with
phenomena that are NOT scientifically
testable
– Example: Faith based philosophies
 Many questions can be explored
through investigation and there are 3
types of investigation: descriptive,
comparative & experimental
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3 Types of Investigations

Descriptive
– Example: count the number of owls living
in a forest
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Comparative
– Example: observe similarities & differences
between the wings of a butterfly & the
wings of a wasp
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Experimental
– Example: apply different amounts of
fertilizer to plants to explore how fertilizer
levels affect plant growth
What type of investigation is
this?
 Examine
the
differences
between
leaves from a
oak tree and
leaves from a
cedar tree
 Comparative
What type of investigation is
this?
 Over
a three
month time
period
observe the
behavior of
rhesus
monkeys
 Descriptive
What type of investigation is
this?
 Test
the affect
of varying
temperatures
on the
hatching rate
of frog eggs
 Experimental
For an experimental
investigation, use….
THE SIX STEPS OF THE
SCIENTIFIC METHOD
(1) Observe and State a Problem
Asking
a question
(2) Form a Hypothesis

Proposed explanation (If, then
statement)
(3) Test the Hypothesis (Design
an experiment)
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Variables – factors that can change
3 Categories of Variables:
1. Manipulated Variable (independent
variable) – factor that scientists purposely
change
2. Responding Variable (dependent
variable) – factor that may change
because of the manipulated variable and
that scientists want to observe
3. Controlled Variables – factors that
scientists purposely keep the same
(3) Test the Hypothesis, cont.
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A controlled experiment is set up with a
control group and the experimental
group
All the groups in an experiment are
treated exactly the same except for the
manipulated variable
In the experimental group, the
manipulated variable is being changed
The control group is used as a standard
of comparison (it may consist of objects
that are not changed in any way or
objects that are being treated in the
usual way – natural conditions)
(4) Record and Analyze Results
Plant Growth
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90
Data - written
80
observations,
70
60
Height
charts &
50
(cm)
40
graphs
30
20
10
0
10
20
30
40
Days
Plant #1
Plant #2
Plant #3
(4) Record and Analyze Results, cont.

Observations can be quantitative
OR qualitative
– Quantitative data involves
measurement, like counting the
number of owls observed
– Qualitative data uses words to
describe the properties that were not
measured, like noting that a bacterial
colony growing in a petri dish was
circular in shape & orange in color
(5) Form a Conclusion
 Evaluate
the
hypothesis
(Do the
results
support the
hypothesis?)
(6) Repeat the Experiment
 Especially
important for work
to be published
Extra Science Definitions

Inference
– Reasonable conclusion based on
observations and clues

Prediction
– Guess about what will happen next based
on observations and experiences; can use
data to predict trends

Theory
– Well-established, reliable explanation that
has been tested in many conditions by
multiple people; Example: cell theory
Fact
vs.
 Something
known to
be true
Theory
When a
hypothesis is
tested and
confirmed by
scientists
 Can change as
new data
becomes
available
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