explorations in the nature of science in the nature of science ... than it answers, ... scientists...
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Explorations in the Nature
of Science
Dr. Paul Narguizian
Professor of Biology and Science Education
California State University, Los Angeles
Email: [email protected]
Web Page: http://www.calstatela.edu/faculty/pnargui/
The human family may have evolved half a million years earlier than
we thought
• A lower jaw found in Africa.
• Homo genus -- the one that we ourselves belong to --
evolved some 400,000 years earlier than previously
assumed.
• The 2.8 million-year-old fossil is from a crucial time in
the evolution of our ancestors but one that has yielded
scant few skeletal remains to researchers eager to fill
the gaps of our knowledge.
• Until now, the oldest member of the Homo genus was
thought to be Homo habilis ("handy man") who lived
some 2.3 million years ago.
• New fossil, described in a pair of papers
published Wednesday in Science, is significantly
older, and seems to link more recent members of the
genus to the primates that preceded them.
• "One of the most important time intervals for
understanding the emergence of our evolutionary
lineage, Homo, is the period between 3 [million] and 2
million years," William Kimbel, author of one of the
studies and director of the Institute of Human Origins
at Arizona State University, said during a news
teleconference on Wednesday. "Ironically, it is one of
the least well-known time periods in the human fossil
record.“
The new fossil just steps from where it was spotted by
Chalachew Seyoum, an ASU grad student from Ethiopia.
(Kaye Reed)
Published: March 04, 2015
• Important because it represents the gap
between the time when Australopithecus (the
genus that includes individuals such as the
famous Lucy, a member of the species A.
afarensis) flourished and when Homo hit the
scene.
• While researchers can find clear evidence
of Australopithecus 3 million years ago and
multiple, co-existing species of Homo 2 million
years ago, they don't usually find much in
between.
• This new fossil isn't just special because it
falls into the right date range, however.
• The piece of lower jaw, which was found in the
Afar region of Ethiopia, shares similarities with
both Australopithecus and Homo.
• The researchers report that a sloping chin
links the set of teeth to the ape-
like Australopithecus, but narrow, symmetrical
molars and jaw proportions place it clearly in
the Homo genus.
• According to the geologists who dated the fossil
by analyzing the volcanic ash and sediment it
was found in, these early hominids lived in a
climate not unlike today's Serengeti -- dry with
lots of grass, probably with rivers, but few trees.
• There's some evidence that climate change
around 2.5 million to 3 million years ago may
have left the region extremely dry and difficult to
live in, and some have suggested that this event
led to the appearance of hominids as
Australopithecus struggled.
• It now looks as though the first examples
of Homo probably came before dramatic climate
shifts, so it's hard to say how much this may
have had to do with the emergence of the first
members of the genus.
• "What we do know is that early Homo could live
in this fairly extreme habitat," Arizona State
professor and study author Kaye Reed said,
"and that apparently Lucy’s species,
Australopithecus afarensis, could not."
A close-up of the mandible. (Kaye Reed)
• In a related paper published Wednesday in Nature,
researchers presented a new reconstruction of Homo
habilis, the former oldest known example of the
genus.
• In what's believed to be a more accurate
reconstruction of the skull of the species, the shape
was surprisingly primitive. This may further indicate
that the first ancestor of the genus lineage appeared
quite early, giving the genus time to diversify into
multiple species -- some more distinctly "human" from
the ape-like Australopithecus than others -- by the
time habilis came along.
• These discoveries, the researchers said during the
teleconference, help narrow down the period during
which archaeologists should search for clues about
the transition from ape to man.
• "Of course this specimen raises many more questions
than it answers, and those questions will only be
resolved by further fieldwork," study leader Brian
Villmoare of the University of Nevada at Las Vegas
said during the news conference. "Hopefully, with
future discoveries in our ongoing fieldwork, we will be
able to speak to many of those questions."
Thinking about science: A survey on the nature and process
of science
For each item, select the answer that best reflects your views.
1) Scientific knowledge is built through a complex process that relies, in part, on observations of nature.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree agree
2) If an observation is made in the correct way, its meaning is straightforward and is not subject to
interpretation.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree agree
3) Scientific theories may be changed because scientists reinterpret existing observations.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree agree
4) The process of science allows scientists to definitively prove or disprove hypotheses and theories.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree agree
5) Even brand new hypotheses are usually based on evidence.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree agree
6) Because they are inherently tentative, accepted scientific theories and hypotheses are unreliable.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree agree
7) Well -supported hypotheses become theories, and well -supported theories become laws.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree agree
8) Accepted scientific theories are well-supported explanations for a broad set of natural phenomena.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree agree
9) All cultures conduct scientific research the same waybecause science is universal and independent of
society and culture.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree agree
10) Scientific research is not influenced by society and culture because scientists are trained to conduct
“pure,” unbiased studies.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree agree
11) The process of science in volves a system of checks and balances to ensure that work is of high quality
and that evidence is interpreted in an objective way.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree agree
12) Unlike many other professions, science is almost always a solitary endeavor.
1 2 3 4 5
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disagree agree
13) Science has had a tremendous impact on modern societies.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree agree
14) Science is pure; scientists strive to do their work without considering its potential applications.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree agree
15) Scientists do not use their imagination and creativity because these conflict with their logical reasoning.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree agree
16) Scientists do not use their imagination and creativity because these can interfere wit h objectivity.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree agree
17) Scientists always follow the same step -by-step scientific method.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree agree
18) Scientific studies frequently involve surprises; many factors influence the direction an investigation
takes.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree agree
19) Science is an ongoing process of building reliable knowledge about the natural world.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree agree
20) Scientific investigations usually come to a definitive end, allowing the science to move on to a brand
new question.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree agree
21) Laboratory experiments are the main method used to develop scientific knowledge.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree agree
22) The same hypothesis or theory is often tested in many different ways.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree agree
23) Scientific testing involves figuring out what we would expect to observe if a particular explanation were
true and seeing if we actually make that observation.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree agree
24) The aim of scientific testing is to prove a hypothesis correct.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree agree
25) Science can help inform decisions related to morality but cannot directly make moral judgments about
what is good and bad.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree
26) Science could disprove the existence of supernatural beings like God.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree agree
27) I personally think that science is boring.
1 2 3 4 5
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disagree agree
28) I personally think that science is extremely valuable for socie ty.
1 2 3 4 5
Strongly Disagree Unsure Agree Strongly
disagree agree
Views of Nature of Science Questionnaire (VNOS)
1. What, in your view, is science? What makes science (or a scientific discipline such as physics, biology, etc.)
different from other disciplines of inquiry (e.g., religion, philosophy)?
2. Is there a difference between a scientific theory and a scientific law? Give an example to illustrate your answer.
3. After scientists have developed a scientific theory (e.g., atomic theory, evolution theory), does the theory ever
change?
If you believe that scientific theories do not change, explain why. Defend your answer with examples.
If you believe that scientific theories do change: (a) Explain why theories change; (b) Explain why we bother to
learn scientific theories. Defend your answer with examples.
4. What is an experiment?
5. Does the development of scientific knowledge require experiments?
If yes, explain why. Give an example to defend your position.
If no, explain why. Give an example to defend your position.
6. Scientists perform experiments/investigations when trying to find answers to the questions they put forth. Do
scientists use their creativity and imagination during their investigations?
If yes, then at which stages of the investigations do you believe scientists use their imagination and creativity:
planning and design, data collection, after data collection? Please explain why scientists use imagination and
creativity. Provide examples if appropriate.
If you believe that scientists do not use imagination and creativity, please explain why. Provide examples if
appropriate.
7. How are science and art similar? How are they different?
8. Is there a difference between scientific knowledge and opinion? Give an example to illustrate your answer.
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Observation• Observation: In everyday language, the word
observation generally means something that we've
seen with our own eyes.
• In science, the term is used more broadly. Scientific
observations can be made directly with our own
senses or may be made indirectly through the use
of tools like thermometers, pH test kits, Geiger
counters, etc.
• We can't actually see beta particles, but we can
observe them using a Geiger counter.
Understanding Science. 2014. University of California Museum of
Paleontology. 10 October 2014
<http://www.understandingscience.org>.
Prediction• Prediction: In everyday language,
prediction generally refers to something
that a fortune teller makes about the
future. In science, the term prediction
generally means "what we would expect
to happen or what we would expect to
observe if this idea were accurate."
Scientific Fact• Fact: Facts are statements that we know to be true through direct
observation.
• In everyday usage, facts are a highly valued form of knowledge because
we can be so confident in them.
• Scientific thinking, however, recognizes that, though facts are important,
we can only be completely confident about relatively simple statements.
• For example, it may be a fact that there are three trees in your backyard.
However, our knowledge of how all trees are related to one another is not
a fact; it is a complex body of knowledge based on many different lines of
evidence and reasoning that may change as new evidence is discovered
and as old evidence is interpreted in new ways.
• Though our knowledge of tree relationships is not a fact, it is broadly
applicable, useful in many situations, and synthesizes many individual
facts into a broader framework.
• Science values facts but recognizes that many forms of knowledge are
more powerful than simple facts.Understanding Science. 2014. University of California Museum of
Paleontology. 10 October 2014
<http://www.understandingscience.org>.
• For instance, we have the facts that bears have
hair—a set of observations we wish to explain
(Fitzhugh 2009).
American black bear
Ursus americanus (Pallas, 1780)
http://www.nhm.org/site/explore-exhibits/permanent-exhibits/north-
american-mammals/black-bear
How Can FACTS be Used at the NHM LA?
How Can FACTS be Used in
Science?• In brief, facts or shared data and observations are the raw
materials of science that may be used in a variety of ways.
• Facts may be formed into a law or “a descriptive
generalization about how some aspect of the natural world
behaves under stated circumstances” (National Academy of
Sciences (NAS), 1998, p. 5). Another distinct kind of scientific
knowledge is a theory which is “a well substantiated
explanation of some aspect of the natural world that can
incorporate facts, laws, inferences, and tested hypotheses”
(p. 5).
HYPOTHESIS
• How would you incorporate the aforementioned
fact(s) into a hypothesis?
• An evolutionary biologist might then present the
following hypothesis:
• As the result of random mutation, hair originated in
the earliest mammals, which were diminutive and
likely nocturnal creatures, living among the
dinosaurs, and there was a selective advantage to
the presence of hair because it ensured a constant
body temperature.
Scientific Hypothesis• In everyday language, the word hypothesis usually refers to an
educated guess — or an idea that we are quite uncertain about.
• Scientific hypotheses, however, are much more informed than any
guess and are usually based on prior experience, scientific background
knowledge, preliminary observations, and logic. In addition,
hypotheses are often supported by many different lines of evidence —
in which case, scientists are more confident in them than they would be
in any mere "guess."
• To further complicate matters, science textbooks frequently misuse the
term in a slightly different way. They may ask students to make a
hypothesis about the outcome of an experiment (e.g., table salt will
dissolve in water more quickly than rock salt will). This is simply a
prediction or a guess (even if a well-informed one) about the outcome
of an experiment.
Scientific Hypothesis
• Scientific hypotheses, on the other hand, have explanatory power — they are
explanations for phenomena. The idea that table salt dissolves faster than rock
salt is not very hypothesis-like because it is not very explanatory. A more
scientific (i.e., more explanatory) hypothesis might be "The amount of surface
area a substance has affects how quickly it can dissolve. More surface area
means a faster rate of dissolution." This hypothesis has some explanatory power
— it gives us an idea of why a particular phenomenon occurs — and it is
testable because it generates expectations about what we should observe in
different situations.
• If the hypothesis is accurate, then we'd expect that, for example, sugar
processed to a powder should dissolve more quickly than granular sugar.
Students could examine rates of dissolution of many different substances in
powdered, granular, and pellet form to further test the idea.
• The statement "Table salt will dissolve in water more quickly than rock salt" is
not a hypothesis, but an expectation generated by a hypothesis. Textbooks and
science labs can lead to confusions about the difference between a hypothesis
and an expectation regarding the outcome of a scientific test.
Scientific Hypothesis• Hypothesis: A testable statement about the
natural world that can be used to build more
complex inferences and explanations (NRC,
1998).
• A hypothesis in the classroom setting usually
involves a prediction followed by an
explanation.
Scientific Hypothesis
• A proposed explanation for a fairly narrow set
of phenomena, usually based on prior
experience, scientific background knowledge,
preliminary observations, and logic.
Scientific Law vs. Theory• In the language of science, laws and
theories are related but distinct kinds of
scientific knowledge.
Scientific Law
• Law: A descriptive generalization about
how some aspect of the natural world
behaves under stated circumstances
(NRC, 1998). Laws include predictions
made about natural phenomena.
Scientific Theory• Theory: A well-substantiated
explanation/mechanism of some aspect of the
natural world that can incorporate facts, laws,
inferences, and tested hypotheses (NRC, 1998).
Theories explain how the law works (McComas,
2003).
• Scientific theories are explanations that are
based on lines of evidence, enable valid
predictions, and have been scientifically tested
in many ways.
Scientific Law vs. Theory
• Sonleitner, (1989) makes the point that
theory and law, are qualitatively different in
what they are and what they do.
• He states that laws are generalizations
about phenomena while theories are
explanations of phenomena.
• Theory and law are not distinguished by
their degree of verification.
Laws and Theories
• The Law of
Biological Evolution
• The Theory of
Natural Selection
http://evolution.berkeley.edu/evosite/evo101/IIAFamilytree.shtml
Natural Selection
• The theory of natural selection, which
describes the mechanism by which
inherited traits that affect survivability or
reproductive success can cause changes in
populations of living organisms over
generations, is supported by extensive
studies of DNA, fossils and other types of
scientific evidence.
Mechanisms of Biological
Evolution• The main – but certainly not the only –
mechanism of biological evolution is natural selection (Scott, 2005).
• Others include:– Mutation and Genetic Variation
• Mendelian Population Genetics– Selection and mutation
• Mendelian Population Genetics– Migration, Drift, Non-random Mating/Inbreeding
• Evolution at Multiple Loci– Linkage, sex, and quantitative genetics
Biological Evolution Defined
• Biological Evolution is defined as the change in allele frequencies (where alleles are versions of the same gene that differ in their base sequence) within populations.
(Freeman and Herron, 2004)
Biological Evolution Defined
• Biological Evolution the changes
in the genetic composition of a
population with the passage of each
generation.
(Volpe & Rosenbaum, 2000).
Natural Selection Defined• Natural Selection is defined as the process
in nature that causes evolution through
differential reproductive success among
members of a population; that success
depends on genetically based and heritable
variation in characteristics that confer relative
advantage or disadvantage to the bearer.(Price, 1996)
Natural Selection Defined
• Natural Selection is defined as those
individuals in a population that (genetically)
are better able to survive and reproduce in a
particular environment leave more offspring,
which in turn carry a higher frequency of
genes promoting adaptation to that
environment.(Scott, 2005)
Laws and Theories
• The Law of
Biological Evolution
• The Theory of
Natural Selection
http://evolution.berkeley.edu/evosite/evo101/IIAFamilytree.shtml
Laws and Theories• Laws consist primarily as statements or
generalizations made about naturalphenomena. They may also be able to predict natural phenomena.
• Theories, however, consist of the explanation/ mechanism for how the law works (McComas, 2003). Scientific theories are explanations that are based on lines of evidence, enable valid predictions, and have been scientifically tested in many ways.
• Examples? Cell Theory?
The Cell Theory or Cell Law
(?)• The three parts to the cell theory are as
described below:
1. All living organisms are composed of one or
more cells.
2. The cell is the basic unit of structure,
function, and organization in all organisms.
3. All cells come from preexisting, living cells.
http://en.wikipedia.org/wiki/Cell_theory
Dalton’s Atomic Theory or Law (?)
1. Each element is composed of extremely small particles
called atoms.
2. All atoms of a given element are identical; the atoms of
different elements are different and have different
properties (including different masses).
3. Atoms of an element are not changed into different types
of atoms by chemical reactions; atoms are neither created
nor destroyed in chemical reactions.
4. Compounds are formed when atoms of more than one
element combine; a given compound always has the
same relative number and kind of atoms.(Brown, LeMay, Bursten ,1997)
Newton’s Laws of Motion1. First law: An object at rest remains at rest unless acted
upon by a force. An object in motion remains in motion, and
at a constant velocity, unless acted upon by a force.
2. Second law: The acceleration of a body is directly
proportional to, and in the same direction as, the net force
acting on the body, and inversely proportional to its mass.
Thus, F = ma, where F is the net force acting on the object,
m is the mass of the object and a is the acceleration of the
object.
3. Third law: When one body exerts a force on a second
body, the second body simultaneously exerts a force equal
in magnitude and opposite in direction to that of the first
body.http://en.wikipedia.org/wiki/Newton's_laws_of_motion
Theory of General Relativity• General relativity is a theory of gravitation
that was developed by Albert Einstein
between 1907 and 1915. According to
general relativity, the observed gravitational
effect between masses results from their
warping of spacetime.
James Watson’s Definition…• “Let us not beat around the bush – the common
assumption that evolution through natural selection is a ‘theory’ in the same way as string theory is a theory, is wrong. Evolution is a Law … that is well substantiated as any other natural law, whether the Law of Gravity, the Laws of Motion or Avogadro’s Law. Evolution is a fact, disputed only by those who choose to ignore the evidence, put their common sense on hold, and believe instead that unchanging knowledge and wisdom can be reached only by revelation.
James D. Watson (2005). Darwin the Indelible Stamp:
The Evolution Of An Idea.
• The Natural History Museum of Los
Angeles can provide the opportunity for
students to understand the roles and
discrete contributions of laws and theories
while providing opportunities for them to
question their preconceived notions about
these and other related issues in the nature
of science.
http://cbsla.files.wordpress.com/2012/11/natural-history-museum.jpg
https://pbs.twimg.com/profile
_images/1384598458/Polar-
Bear-6108-crop.jpg
Age of Mammals
• Age of Mammals tells an epic
evolutionary story that spans 65 million
years! But its theme can be distilled into
just six words:
• Continents move.
• Climates change.
• Mammals evolve. http://www.nhm.org/site/explore-exhibits/permanent-exhibits/age-of-mammals
Dinosaur Hall
• Dinosaur Hall at the Natural History
Museum of Los Angeles, is one of the
most extraordinary dinosaur exhibits in the
world.
• Inside are more than 300 real fossils, and
20 complete dinosaurs and ancient sea
creatures.
http://www.nhm.org/site/explore-exhibits/permanent-exhibits/dinosaur-hall
Dinosaur Hall
Exploration:
1.) Scientific Claim: Birds Evolved from Dinosaurs.
2.) Visit Dinosaur Hall at the Natural History Museum of Los
Angeles.
3.) Provide a fact, hypothesis, law, and theory from Dinosaur
Hall to support the aforementioned claim “Birds Evolved from
Dinosaurs.”
Goal of NGSSDevelop standards that will be rich in content and practice, arranged in a coherent manner across disciplines and grades to provide all students an internationally benchmarked science education.
Less emphasis on: More emphasis on:
Discrete Facts Conceptual understanding with a focus on depth over breadth
Isolated investigation and experimentation process skills
Integration of science and engineering practices with content
Student acquisition of information
Student understanding and use of scientific knowledge within and across science disciplines, and science and engineering practices
Numerous Standards Limited number of disciplinary Core Ideas and Cross Cutting Concepts that unify the study of science and engineering
Uneven articulation throughout grade levels
Learning progressions that develop K-12
*Presentation to the State Board of Education, July 10, 2013
AppendicesA Conceptual Shifts
B Responses to May Public Feedback
C College and Career Readiness
D All Standards, All Students
E Disciplinary Core Idea Progressions in the NGSS
F Science and Engineering Practices in the NGSS
G Crosscutting Concepts in the NGSS
H Nature of Science in the NGSS
I Engineering Design in the NGSS
J Science, Technology, Society, and the Environment
K Model Course Mapping in Middle and High School
L Connections to Common Core State Standards in Mathematics
M Connections to Common Core State Standards in English Language Arts
The Nature of Science and NGSSThe nature of science is included in the Next Generation Science Standards. Here we present the NOS Matrix. The basic understandings about the nature of science are:
1. Scientific Investigations Use a Variety of Methods
2. Scientific Knowledge is Based on Empirical Evidence
3. Scientific Knowledge is Open to Revision in Light of New Evidence
4. Scientific Models, Laws, Mechanisms, and Theories Explain Natural Phenomena
5. Science is a Way of Knowing
6. Scientific Knowledge Assumes an Order and Consistency in Natural Systems
7. Science is a Human Endeavor
8. Science Addresses Questions About the Natural and Material World
Overview
One goal of science education is to help students understand the nature of scientific knowledge. This matrix presents eight major themes and grade level
understandings about the nature of science. Four themes extend the scientific and engineering practices and four themes extend the crosscutting concepts. These
eight themes are presented in the left column. The matrix describes learning outcomes for the themes at grade bands for K-2, 3-5, middle school, and high
school. Appropriate learning outcomes are expressed in selected performance expectations and presented in the foundation boxes throughout the standards.
Understandings about the Nature of Science Categories K-2 3-5 Middle School High School
Scientific Investigations Use a
Variety of Methods
Science investigations
begin with a question.
Scientist use different ways to study the world.
Science methods are determined
by questions.
Science investigations use a variety of methods, tools, and
techniques.
Science investigations use a variety of methods and
tools to make measurements and observations.
Science investigations are guided by a set of values to ensure accuracy of measurements, observations,
and objectivity of findings.
Science depends on evaluating proposed explanations.
Scientific values function as criteria in distinguishing
between science and non-science.
Science investigations use diverse methods and do not always use the
same set of procedures to obtain data.
New technologies advance scientific knowledge.
Scientific inquiry is characterized by a common set of values that include: logical thinking, precision, open-mindedness, objectivity,
skepticism, replicability of results, and honest and ethical reporting of findings.
The discourse practices of science are organized around disciplinary
domains that share exemplars for making decisions regarding the values, instruments, methods, models, and evidence to adopt and use.
Scientific investigations use a variety of methods, tools, and techniques to revise and produce new knowledge.
Scientific Knowledge is Based on Empirical
Evidence
Scientists look for
patterns and order when making observations
about the world.
Science findings are based on
recognizing patterns.
Scientists use tools and
technologies to make accurate measurements and observations.
Science knowledge is based upon logical and
conceptual connections between evidence and explanations.
Science disciplines share common rules of obtaining and evaluating empirical evidence.
Science knowledge is based on empirical evidence.
Science disciplines share common rules of evidence used to evaluate explanations about natural systems.
Science includes the process of coordinating patterns of evidence with
current theory.
Science arguments are strengthened by multiple lines of evidence supporting a single explanation.
Scientific Knowledge is Open to Revision in Light of New Evidence
Science knowledge can change when new
information is found.
Science explanations can change based on new evidence.
Scientific explanations are subject to revision and improvement in light of new evidence.
The certainty and durability of science findings
varies.
Science findings are frequently revised and/or reinterpreted based on new evidence.
Scientific explanations can be probabilistic.
Most scientific knowledge is quite durable but is, in principle, subject to change based on new evidence and/or reinterpretation of existing
evidence.
Scientific argumentation is a mode of logical discourse used to clarify
the strength of relationships between ideas and evidence that may result in revision of an explanation.
Science Models, Laws, Mechanisms, and
Theories Explain Natural Phenomena
Scientists use drawings, sketches, and models as a way to communicate
ideas.
Scientists search for
cause and effect
relationships to explain natural events.
Science theories are based on a body of evidence and many tests.
Science explanations describe
the mechanisms for natural events.
Theories are explanations for observable phenomena.
Science theories are based on a body of evidence
developed over time.
Laws are regularities or mathematical descriptions of
natural phenomena. A hypothesis is used by scientists as an idea that
may contribute important new knowledge for the evaluation of a scientific theory.
The term "theory" as used in science is very different
from the common use outside of science.
Theories and laws provide explanations in science, but theories do not with time become laws or facts.
A scientific theory is a substantiated explanation of some aspect of the
natural world, based on a body of facts that has been repeatedly
confirmed through observation and experiment, and the science community validates each theory before it is accepted. If new
evidence is discovered that the theory does not accommodate, the theory is generally modified in light of this new evidence.
Models, mechanisms, and explanations collectively serve as tools in
the development of a scientific theory.
Laws are statements or descriptions of the relationships among observable phenomena.
Scientists often use hypotheses to develop and test theories and
explanations.
Understandings about the Nature of Science
Categories K-2 3-5 Middle School High School Science is a Way of
Knowing Science knowledge helps
us know about the world.
Science is both a body of
knowledge and processes
that add new knowledge.
Science is a way of knowing that is used by many people.
Science is both a body of knowledge and the processes
and practices used to add to that body of knowledge.
Science knowledge is cumulative and many people, from many generations and nations, have contributed to science knowledge.
Science is a way of knowing used by many people, not
just scientists.
Science is both a body of knowledge that represents a current
understanding of natural systems and the processes used to refine,
elaborate, revise, and extend this knowledge.
Science is a unique way of knowing and there are other ways of knowing.
Science distinguishes itself from other ways of knowing through use of
empirical standards, logical arguments, and skeptical review.
Science knowledge has a history that includes the refinement of, and
changes to, theories, ideas, and beliefs over time.
Scientific Knowledge
Assumes an Order and
Consistency in Natural Systems
Science assumes natural events happen today as
they happened in the past.
Many events are repeated.
Science assumes consistent patterns in natural systems.
Basic laws of nature are the same everywhere in the universe.
Science assumes that objects and events in natural systems occur in consistent patterns that are
understandable through measurement and observation.
Science carefully considers and evaluates anomalies in
data and evidence.
Scientific knowledge is based on the assumption that natural laws operate today as they did in the past and they will continue to do so in
the future.
Science assumes the universe is a vast single system in which basic
laws are consistent.
Science is a Human Endeavor
People have practiced science for a long time.
Men and women of
diverse backgrounds are
scientists and engineers.
Men and women from all cultures and backgrounds choose careers as scientists
and engineers.
Most scientists and engineers
work in teams.
Science affects everyday life.
Creativity and imagination are important to science.
Men and women from different social, cultural, and ethnic backgrounds work as scientists and engineers.
Scientists and engineers rely on human qualities such
as persistence, precision, reasoning, logic, imagination
and creativity.
Scientists and engineers are guided by habits of mind
such as intellectual honesty, tolerance of ambiguity, skepticism and openness to new ideas.
Advances in technology influence the progress of
science and science has influenced advances in technology.
Scientific knowledge is a result of human endeavor, imagination, and creativity.
Individuals and teams from many nations and cultures have
contributed to science and to advances in engineering.
Scientists’ backgrounds, theoretical commitments, and fields of endeavor influence the nature of their findings.
Technological advances have influenced the progress of science and
science has influenced advances in technology.
Science and engineering are influenced by society and society is influenced by science and engineering.
Science Addresses Questions About the
Natural and Material World.
Scientists study the
natural and material world.
Science findings are limited to
what can be answered with empirical evidence.
Scientific knowledge is constrained by human capacity,
technology, and materials.
Science limits its explanations to systems that lend
themselves to observation and empirical evidence.
Science knowledge can describe consequences of
actions but is not responsible for society’s decisions.
Not all questions can be answered by science.
Science and technology may raise ethical issues for which science, by itself, does not provide answers and solutions.
Science knowledge indicates what can happen in natural systems—not
what should happen. The latter involves ethics, values, and human decisions about the use of knowledge.
Many decisions are not made using science alone, but rely on social
and cultural contexts to resolve issues.
Nature of Science understandings most closely associated with Practices
Nature of Science understandings most closely associated with Crosscutting Concepts
Resources• Next Generation Science Standards
www.nextgenscience.org/
• CDE updates to the NGSS
www.cde.ca.gov/pd/ca/sc/ngssintrod.asp
• http://www.cde.ca.gov/pd/ca/sc/ngssstandard
s.asp
• NSTA Common Core Resources
www.nsta.org/about/standardsupdate
Evolution Websites• University of California Museum of
Paleontology at UC Berkeley and the
National Center for Science Education:
• http://undsci.berkeley.edu/• This is a good website for topics that explore
classroom activities, teaching tools, a K-16
conceptual framework, tips, and strategies for
integrating the process of science into your
teaching, and more.
ReferencesAllen, G. and J. Baker. 2001. Biology: Scientific Process and Social Issues. Bethesda, Md.: Fitzgerald
Science Press, Inc.
Bybee, R. W. (Ed.) 2004. Evolution in Perspective: The Science Teacher’s Compendium. Arlington, VA: NSTA Press.
Campbell, N.A., Reece, J.B., and Mitchell, L.G. 1999. Biology (5th ed.). Menlo Park, CA: Benjamin Cummings.
Darwin, C. 1964. On the Origin of Species (Facsimile 1st ed.). Cambridge, MA: Harvard University Press.
Freeman, S. & Herron, J.C. 2004. Evolutionary analysis (3rd. Ed). Upper Saddle River, NJ: Pearson/Prentice Hall.
Gould, J.A. 1992. Classical Philosophical Questions. 9th ed. Upper Saddle River, N.J.: Prentice Hall.
Miller, K.R. 2006. Presentation. NSTA Conference. Anaheim, CA.
Miller, K. R. 1999. Finding Darwin’s God. New York, NY: Harper Collins.
Narguizian, P. 2004. Understanding the nature of science through evolution. The Science Teacher 71(9): 40-45.
National Academy of Sciences. (2004). Evolution in Hawaii: A Supplement to Teaching About Evolution and the Nature of Science, by Steve Olson. Washington, DC: The National Academies Press.
National Research Council. 1996. National Science Education Standards. Washington, DC: National Academy Press.
Pennock, R.T. (2005). On teaching evolution and the nature of science. In J. Cracraft & R.W. Bybee (Eds.), Evolutionary science and society: Educating a new generation (pp.7-12). Washington, DC: AIBS/BSCS.
Peterson, G. R. 2002. The intelligent design movement: Science or ideology? Zygon 37(1): 7-23.
Price, P.W. (1996). Biological evolution. New York: Saunders College Publishing.
Scott, E.C. (2005). Evolution vs. creationism. Berkeley, CA: University of California Press.
University of California Museum of Paleontology at UC Berkeley and the National Center for Science Education: evolution.berkeley.edu/evosite/evohome.html
Volpe, E.P. & Rosenbaum, P.A. (2000). Understanding evolution. New York: McGraw Hill.
Key Concepts• A scientific theory is an explanation inferred from multiple
lines of evidence for some broad aspect of the natural world
and is logical, testable, and predictive. As new evidence
comes to light, or new interpretations of existing data are
proposed, theories may be revised and even change;
however, they are not tenuous or speculative.
• A scientific hypothesis is an inferred explanation of an
observation or research finding; while more exploratory in
nature than a theory, it is based on existing scientific
knowledge.
• A scientific law is an expression of a mathematical or
descriptive relationship observed in nature. It also has
predictive power.