1.
The Nature of Science

2.
The Nature of Science
To be scientifically literate, science
students should have deeper
understandings of science that studying
the Nature of Science (NOS) provides.

3.
Write an account
of what you think
happened based
on what you see
here.
NOS Example

4.
How does your story change?
NOS Example
continued

5.
NOS Example
How does your story change?

6.
What do you observe?
What do you infer?
Compare what you think now
to your earlier written accounts.
NOS Example
continued

7.
Some Aspects of NOS
• Scientific knowledge is tentative.
• Scientific knowledge has basis in empirical
evidence.
• There is a difference between data and evidence.
• Scientific laws and theories are separate kinds of
scientific knowledge.
• Scientific knowledge is based upon observations
and inferences.
• Scientific knowledge is heavily dependent upon
theories.

8.
Some Aspects of NOS
Continued
• Scientific knowledge is created from human
imagination and logical reasoning.
• Scientific knowledge can be obtained by a variety
of scientific methods.
• Scientific observations are inherently subjective
based on interpretations.
• Science is a human endeavor influenced by
society and culture.

9.
Observation and Inference
• There are differences between observations and
the inferences made based on observations.
• Based on the same data, and scientists’ prior
experiences, different inferences can be made,
which lead to difference conclusions. Some of
these are right and some are wrong.
• Attempting to sort this out is what science is
about!

10.
Scientific Theory and
Scientific Laws

11.
Scientific method
• Process used by scientists to solve problems

12.
Theory
• In everyday usage, “theory” often refers
to a hunch or a speculation. When people
say, “I have a theory about why that
happened,” they are often drawing a
conclusion based on partial or inconclusive
evidence. Scientists have hunches, too, but
they call them hypotheses, which are the
starting point of all good science.

13.
Scientific theory
• A scientific definition of theory is quite
different from the everyday meaning of the
word. A scientific theory refers to a
comprehensive explanation of some aspect
of nature that unifies a vast body of reliable
knowledge. In other words, a theory is
born when a substantial number of
hypotheses point to the same conclusion

14.
• A simple example of a scientific theory is
the Heliocentric Theory which states that the
sun is the center of our solar system. Another
example would be Cell Theory which states
that all living things are composed of cells.
Few people would refer to either of these
theories as “hunches.” More likely, in
everyday language, these theories would be
called scientific facts.
• In science, a Theory:
– Explains a natural phenomenon.
– Predicts future occurrences or observations of the same
kind.
– Can be tested through experiment or otherwise verified
through empirical observation.
– Is Supported by a vast body of reliable knowledge.

15.
• Reliance on theory is critical to every
branch of science. Many scientific theories
are so well established that no new evidence
is likely to alter them substantially. We all
accept that…
– the Earth orbits the Sun (heliocentric theory),
– living things are made of cells (cell theory),
– matter is composed of atoms (atomic theory),
and
– the Earth's surface is divided into solid plates
that move over geological time (theory of plate
tectonics).
• Each theory has been barraged with
scientific tests and still stands intact.

16.
Scientific Law
• Contrary to common understanding,
scientific theories do not “graduate” to
laws…
• Scientific laws are typically short,
mathematical expressions representing
how nature will behave under certain
conditions. Most theories contain laws, and
more importantly, they explain why laws
work and what they mean.

17.
Scientific method
• Process that people use to solve problems
• Controlled experiment only involves one variable
• Control group- is used sometimes and it is used for
comparison.
• Experimental group Red and blue groups
– Ex. Three corn plants used. One is placed in red light, one in
blue light, and one is placed in white light. They are observed
for two weeks and their growth is recorded.

18.
C. Scientific Method
• Hypothesis - testable prediction
• Theory - explanation of “why”
– based on many observations & experimental
results
• Scientific Law - prediction of “what”
– describes a pattern in nature

19.
C. Scientific Method
Theories and laws are well-accepted by scientists,
but...
They are revised when
new information is
discovered.
THEY ARE NOT SET IN STONE!

20.
C. Scientific Method
1. Determine the problem.
2. Make a hypothesis.
3. Test your hypothesis.
4. Analyze the results.
5. Draw conclusions.

21.
C. Scientific Method
1. Determine the problem.
When the Titanic sank, what happened to the
water level on shore?
2. Make a hypothesis.
The water level rose.
The water level dropped.
The water level stayed the same.

22.
C. Scientific Method
3. Test your hypothesis.
How could we test our hypothesis?
4. Analyze the results.
What happened during our test?
5. Draw conclusions.
Was our hypothesis correct?
Is further testing necessary?

23.
D. Experimental Design
• Experiment - organized procedure for
testing a hypothesis
• Key Components:
– Control - standard for comparison
– Single variable - keep other factors constant
– Repeated trials - for reliability

24.
D. Experimental Design
• Types of Variables
– Independent Variable
• The variable in the experiment that you control
• adjusted by the experimenter
• what you vary
– Dependent Variable
• the result of the independent variable
• changes in response to the indep. variable
• what you measure

25.
D. Experimental Design
• Hypothesis:
Storing popcorn in the freezer makes it pop better.
• Control:
Popcorn stored at room temp.

26.
D. Experimental Design
• Single variable:
Storage temperature
• Constants:
Popcorn brand
Freshness
Storage time
Popper

27.
D. Experimental Design
• Independent Variable:
Storage temperature
• Dependent Variable:
Number of unpopped kernels

28.
Scientists are testing a new drug on 6
patients to see how it effects the growth
of breast cancer. Identify how you would
do control group, experimental group.
Also, identify the independent and
dependent variables.