Transcript Big Idea 3 : The Role of Theories, Laws, Hypotheses, and Models

Description
The terms that describe examples of
scientific knowledge, (e.g. "theory,"
"law," "hypothesis," and "model“)
have very specific meanings and
functions within science.
Benchmark Number
& Descriptor
 SC.7.N.3.1
 Recognize and explain the difference
between theories and laws, and give
several examples of scientific theories
and the evidence that supports them.
 SC.7.N.3.2
 Identify the benefits and limitations of
the use of scientific models.
SCIENTIFIC THEORY
 A scientific
explanation to a
pattern in the
natural world
 Many observations
and much evidence
is needed in order
to create a valid
theory.
 Scientific
investigation is a
key part when
creating theories.
 Theories may be
supported by
scientific evidence
at the time but may
be incorrect.
 Evidence may
change with time;
better technology
 Example:
Geocentric (earth
in middle of solar
system) to
Heliocentric
model (sun in
middle of solar
system)
EXAMPLES of
SCIENTIFIC THEORIES
 Big Bang Theory
 The universe has
expanded from hot,
dense, gaseous
conditions.
 Tectonic Plate
Theory
 The surface of the
earth is composed
of tectonic plates,
which move slowly.
 Atomic Theory
 All matter is made
up of atoms.
 Theory of Matter
and Energy
 Matter and Energy
are always
conserved.
 Cell Theory
 Cells form the
foundation, the
basic unit of all
living organisms.
 Theory of
Evolution
 All life on earth
evolved from simple
forms.
SCIENTIFIC LAW
 This is a statement of fact meant to describe, in
concise terms, an action or set of actions. It is
generally accepted to be true and universal, and
can sometimes be expressed in terms of a single
mathematical equation. Scientific laws are
similar to mathematical postulates. They don’t
really need any complex external proofs; they
are accepted at face value based upon the fact
that they have always been observed to be true.
 Specifically, scientific laws must be simple,
true, universal, and absolute. They represent
the cornerstone of scientific discovery, because
if a law ever did not apply, then all science
based upon that law would collapse.
 Some scientific laws, or laws of nature, include
the law of gravity, Newton's laws of motion, the
laws of thermodynamics, Boyle's law of gases,
the law of conservation of mass and energy, and
Hook’s law of elasticity.
http://wilstar.net/theories.htm
EXAMPLES of SCIENTIFIC
LAWS
 Ohm’s Law
 I = V/R
 Relationship
between current,
voltage, and
resistance
 Named after Georg
Ohm
 Newton’s Law s
 Objects at
rest/motion stay at
rest/motion until a
force acts on it.
 Objects will
accelerate in the
direction of the
force (F = M*A).
 Action-Reaction
forces (equal and
opposite)
 Law of Segregation
 For any pair of
characteristics there
is only one gene in a
gamete even
though there are
two genes in
ordinary cells.
 Founder – Gregor
Mendel
 Ideal Gas Law
 Combination of
Charles's and
Boyle’s gas laws.
 Formula: pV = nRT
 Relates pressure,
temperature, and
volume of gasses
For additional laws see this website:
http://en.wikipedia.org/wiki/List_of_scie
ntific_laws_named_after_people
KNOWLEDGE CHECK
1. What is the difference between
a scientific theory and a
scientific law?
2. Can a scientific theory change
over time? Why?
3. List 2 examples of scientific
theory and scientific law.
KNOWLEDGE CHECK
What is the difference between a
scientific theory and a scientific law?
Laws are generalizations about what
has happened; Theories are
explanations of observations (or of
laws).
2. Can a scientific theory change over
time? Why? Yes, as technology
progresses, new evidence can be
discovered helping to justify or
falsify a theory.
3. List 2 examples of scientific theory
and scientific law. Theory: Atomic
theory, Big Bang theory; Law:
Newton’s Laws, Law of Segregation
1.
MODELS
 Models are a visual representation
that help scientists study something
in more depth.
 There are 2 general types of models:
 Physical
Models that you can touch
 Representation of an item they want
to study
 Mathematical
• Made up of math equations and data
• They allow you to calculate things.

MODELS
BENEFITS
 Models can be used
LIMITATIONS
 Scientists must
realize the
for the following:
limitations of
models, especially
 Study objects
when reading the
that are too
information
obtained by them.
small to see
 Because we may not
 Study objects
see an actual picture,
that are too large
models are thoughts
and ideas from our
to see
heads.
 Help explain the  Some calculations
past and the
are very complex,
and computers are
present
needed to find the
 Help predict the
answer.
future
KNOWLEDGE CHECK
1. Why do scientists use models?
2. Describe the two main types of
scientific models.
3. List 2 benefits of using models.
4. List 2 limitations when using
models.
KNOWLEDGE CHECK
1.
Why do scientists use models? To help create
a visual representation when studying
something in more depth.
2.
Describe the two main types of scientific
models. Physical – Hands on model;
Mathematical – equation providing data
1.
List 2 benefits of using models. To help
explain the past and the present, study
objects that are too small/large to see
1.
List 2 limitations when using models. Some
physical models are subjective since they are
based on theories/observations; since some
theories need computers to solve them,
scientists must be able to read and interpret
the data.