Science
According to the National Academy of Sciences,
Science is the use of evidence to construct
testable explanations and predictions of natural
phenomena, as well as the knowledge generated
through this process.
Phenomena are the events that are observed to
happen.
Evidence are observable facts and
measurements of the natural world that can be
used to evaluate hypotheses, theories, and other
scientific explanations.
Scientific Method
How is Science different from other fields of study?
Science uses the scientific inquiry, or the
scientific method
Deductive Reasoning- general to specific
reasoning from general theories to
account for specific experimental results
(theory-data collection-analysis)
Inductive Reasoning- specific to general
reasoning from specific observations
and experiments to more general
theories
(data collection-analysis-theory)
Scientific Method
How is Science different from other fields of study?
Science uses scientific inquiry, or the
scientific method
Deductive Reasoning- general to specific
reasoning from general theories to
account for specific experimental results
(theory-data collection-analysis)
Inductive Reasoning- specific to general
reasoning from specific observations
and experiments to more general
theories
(data collection-analysis-theory)
Scientific Method
Observations
Question
Formulate Hypothesis
Conduct Experiment to test Hypothesis
Analyze Results
Conclusions
Publish
Observation:
The car won’t start when I turn the ignition.
Question:
Hypothesis:
Test hypothesis:
Analyze Results:
Draw Conclusion:
New hypothesis:
Scientific Method
• Observations
– Suggest questions to investigate
• Question
– Why does something happen
Research the question
• Hypothesis
– A testable explanation for an observation
Scientific Method
• Conduct Experiment
– Process of testing a hypothesis or prediction by
gathering data under controlled conditions
– Control vs Experimental Group
Control group: a group that has not been exposed
to some factor (variable). It is used to compare the
experimental group.
Experimental group: a group that has been
exposed to the factor (variable)
Independent variable (IV): the variable you
manipulate that you believe will affect the DV
Dependent variable (DV): the outcome variable,
i.e., variable you measure
Scientific Method
• Collect, organize, analyze data
– Determine whether data is reliable
– Determine whether data supports or does
not support the hypothesis or prediction
– May use statistics
• Compare data from other studies
• Determine relationships
• Determine experimental error
Scientific Method
• Drawing Conclusions
– To understand something not previously
understood
– To produce a model
• Construct a representation of an object, a
system, or a process to help show relationships
given the data
• A model is an explanation supported by data
• Use the model to generate new hypotheses or
predictions
Scientific Method
The last step of the Scientific Method is to publish the
work.
Scientist publish their work so that other scientist can
replicate their work.
If other scientist can not replicate the work, the conclusions
will not be accepted by the scientific community.
Experimental Design
Confounding factors: factors that were not accounted
for in the design that may affect the Independent Variable
Biased sampling: A sampling technique that
does not give you a representative sample.
Method for Reducing Bias:
Randomization in sample selection
Randomization: Ensures that each subject in a
population or each site used for sampling has an
equal opportunity of being selected.
Replication:This is necessary to estimate the
degree of chance variation among samples.
Experimental Design
Sample Size: The larger the sample size, the better. A
larger sample size tends to give you a closer estimate
of the true population mean.
Scientific Method- Theory
A theory is a broad powerful
explanation of events in the natural
world, supported by the results of
many experiments.
– Unifying explanations for a broad range of
observations
– Based on testing a collection of related
hypotheses
– The solid foundation of science
– Can be revised given new evidence
Contrasting Hypotheses,
Theories, and Laws
Scientific Hypothesis
A tentative scientific explanation
that attempts to answer questions
asked about natural phenomena.
A proposed explanation made on
the basis of observation, used to
begin a scientific experiment
Hypothesis
• Based on opinion and observation
• Can NOT be proven true
and can only be
supported
• NEVER EVER EVER
can we call them true
Practice
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Bart believes that mice exposed to microwaves will become extra strong (maybe he's
been reading too much Radioactive Man). He decides to perform this experiment by
placing 10 mice in a microwave for 10 seconds. He compared these 10 mice to another
10 mice that had not been exposed. His test consisted of a heavy block of wood that
blocked the mouse food.
Independent variable (IV):_(The thing that is changed) ____________
____________________________________________________________
Dependent variable (DV):__(The thing that will be measured)
___________________________________________________________
Constants: _(The things that will kept the same)
___________________________________________________
Control: ___(The things that will be kept the same
___________________________________________________
Hypothesis:
If… _____________________________________________________
then… ___________________________________________________
Scientific Theory
A widely accepted, well documented
statement that addresses and
explains many independent
observations of nature.
A broad, powerful explanation of
events in the natural world,
supported by the results of many
experiments
Scientific Theory
A theory explains how nature works
1. should be rational and logical
2. should be relevant
3. should be extensible
Ptolemy (170 A.D.)- geocentric universe,
earth centered universe
Copernicus (1500’s)- heliocentric
universe; sun centered universe
not accepted until 100 years after his
death
Galileo (1600’s)- physicist, astronomer, first to use
scientific method ; confirmed earth revolved
around the sun
Scientific or Natural Law
A description or rule for how
nature appears to behave. A law
has a small likelihood of being
found incorrect.
A Scientific Law describes what
nature does under certain
conditions
Scientific or Natural Law
Mainly found in physics and
chemistry.
Mendel’s Law of Inheritance
Newton’s Law of Gravity
First & Second Laws of Thermodynamics
Matter & Energy
Entropy
It’s YOUR turn now
• Work in groups of 4.
• Come up with a problem that a new student
at AHS might have.
• Use all the steps of the Scientific Method to
find a solution.
• Cycle through the Hypothesis/Experiment
loop at least twice.
The Blind Men and the Elephant (Saxe; 1816-1887)
I.
It was six men of Indostan
To learn much inclined,
Who went to see the elephant
(Though all of them were blind),
That each by observation
Might satisfy their mind.
II.
The First approached the elephant,
And happened to fall
Against his broad sturdy side,
At once began to bawl:
“Bless me!—but the Elephant is very like a wall!”
III.
The Second, feeling of the tusk ,
Cried, “Ho!—what have we here
So very round and smooth and sharp?
To me ‘t is mighty clear
This wonder of an Elephant
Is very like a spear!”
IV.
The Third approached the animal,
And happening to take
The squirming trunk within his hands,
Thus boldly up and spake:
“I see,” quoth he, “the Elephant
Is very like a snake!”
V.
The Fourth reached out his eager hand,
And felt about the knee.
“What most this wondrous beast is like
Is might plain’” quoth he;
“‘T is clear enough the Elephant
Is very like a tree!”
VI.
The Fifth, who chanced to touch the ear,
Said, “E’en the blindest man
Can tell what this resembles most;
Deny the fact who can,
This marvel of an Elephant
Is very like a fan!”
VII.
The Sixth no sooner had begun
About the beast to grope,
Than seizing on the swinging tail
That fell within his scope,
“I see,” quoth he, “the Elephant
Is very like a rope!”
VIII.
And so these men of Indostan
Disputed loud and long,
Each with his own opinion
Exceeding stiff and strong,
Though each was partly in the right,
And all were in the wrong!
Moral.
So, oft in these theological wars
The disputants, I ween,
Rail on in utter ignorance
Of what each other mean,
And prate about an elephant
Not one of them has seen!
The Blind Men and the Elephant, Part 2,
I.
They talked, those men from Indostan
While standing at the door,
Of elephants and how they looked
(This talk was such a bore!),
At last they agreed that the knowledge gained
Required something more.
II.
Perhaps each one in his own way,
Did learn a bit
Of the beast’s elusive mystery,
But just a part of it
With work, they thought, that they might see
The puzzle pieces fit.
III.
‘Twas obvious to all of them
For learning to progress,
That they must share in what they found—
Jointly sort out the mess.
And seek to fully understand
Elephants, more or less.
IV.
Some worked alone and some in teams,
In both the field and lab.
Models were made: some soft, some hard
Some good, some pretty bad.
But when they pooled the useful work,
And truth they made a grab.
V.
They checked each other’s methods out,
Some kept, some put asunder.
To use the ones which passed the test
Reduced the chance of blunder.
Then they’d trust what they had learned
Of elephants’ fine wonders.
VI.
They made great strides in what they knew
Of the nature of the beast.
Of what and where and how and why
They knew much more at least.
For blind men learned how best to learn
And vision soon increased!
Inquiry
In your table groups discuss the
following question.
Compare the similarities and differences
between a hypothesis, scientific theory
and scientific law?