Transcript Enhancing Thinking Skills in Science Context Lesson 8 Analogies in

Enhancing Thinking Skills in
Science Context Lesson 8
Analogies in Science
Activity 1
You are given a piece of A4 paper and two
paper clips. Try to fold the piece of paper
to support the weight of as many books as
you can (i.e. the pile of books are placed
on the folded paper).

Why do you fold the piece of paper in
such way (any related science
concepts or principles)?
The piece of paper is
folded to a ring-shaped
structure.
The ring-shaped paper roll
acts like a pillar (an
example of analogy) and
can support heavy weights.
The piece of paper is
folded to a cylindrical shaped structure.
This cylindrical paper roll
acts like a pillar (an
example of analogy) and
can support heavy
weights, too.
Activity 2
Long time ago a patient suffered from a
disease making him unable to urinate. His
belly was swelling more and more and he
was in great pain. His doctor, Sun
Simiao(孫思邈AD 581-682) thought that his
urinary tract must have been blocked. He
could not think of the treatment right away
and was very frustrated because his patient
might die soon.
Activity 2
He then saw a boy playing music with a
roasted scallion (烤熟的蔥管) by blowing
air through it. It made him think of the
idea to save the patient’s life!
What was Dr Sun’s treatment?
What can a scallion do?
 In what way(s) are urinary tracts
and scallions in common?
Shape?
Property /function?
What can a scallion do?
straw
Hair band
shoelace
string
pen
Vine
basket
 Dr Sun then saw a boy playing music
with a roasted scallion (烤熟的蔥管)
by blowing air through it.
 It made him think of the idea that he
could insert such a tube (by cutting
one end of the tube small and sharp)
into the urinary tract of the patient
and the urine can be sucked out by
mouth.
 Finally he really did so and the
patient was saved.
Discussion questions:
Urinary tracts and scallions are similar.
Dr. Sun used analogy to find a solution
to the problem of his patient.
Analogy
If two things or objects, A and B have
some similar properties, and A has
other special attribute, property W, we
can possibly infer that B also has the
attribute, property W. Analogy is an
inference from a particular object to
another particular object.
Analogy
Object A and object B are similar in
having properties X1, X2, X3, ……
Object A has property W.
It is most likely that Object B also has the
property W.
Analogy
A: X1, X2, X3, ……; W
B: X1, X2, X3, ……
Therefore, B may have property W.
Relationship among analogy,
induction and deduction in science
Generalisation
Induction
Special attribute A
(particular facts or
ideas)
Deduction
Analogy
Special attribute B
(particular facts or
ideas)
(reference: 《類比》王溢然，張耀久(2001))
Activity 3
Below is the data of two solar
system objects, the Earth and the
Mars:
Special features
Earth
Mars (火星)
Shape
spherical
spherical
Moon
one moon
2 moons
1 earth year
1.9 earth year
(remarks:
Neptune-164 earth
year; Uranus-84
earth year)
Orbital period
Surface
temperature
Average 17
degree Celsius
-93 to -3 degree
Celsius
Average density
5500 kg/m3
3900 kg/m3
Surface gravity
1.00 (Earth=
1.00)
0.38
Atmospheric
pressure
1.0 (Earth =
1.00)
0.007
Components
of the
Atmosphere
78%
nitrogen21 %
oxygen 1 %
argon, water
vapour, carbon
dioxide, other
inert gases
95.3 % Carbon
dioxide2.7 %
nitrogen1.6% argon
trace amounts of
oxygen, carbon
monoxide and water
vapour
Water
Abundant
amount of
water
In 2007 scientists
discovered that the
south pole of Mars was
covered by dry ice and
cold water.
Methane
Released as
metabolites of
living
organisms
The presence of
methane was detected
in 2003.
Discussion questions:
1. What are the similar properties between
the Earth and Mars?
2. It is a very distinctive property of the
Earth that there are living creatures on the
Earth. Do you have great confidence to use
Analogy to argue that there would also be
living things on Mars? Please explain your
answer.
Task 1
1. Fill in the blanks:
Wires  (
)
Potential  (
)
Voltage (potential difference) (
Current  (
)
Resistor  (
)
)
Reference website (analogy model):
http://www.ac.www.edu/~vawter/PhysicsNet/Topics/DCCur
rent/WaterFlowAnalog.html
Hydraulic analogy to explain electric circuit
Paddle
Wires
Water pressure
Electrical Potential
Water pipes
Voltage
Electric current
Difference in pressure
between two points
Light bulb
Water current
Pump
Dry cell
2. What are the limits to the above
hydraulic analogy?
We may ask the following questions ourselves:
 In the hydraulic analogy model water would
leak out if there is a hole in the water pipe.
Electric charge would not “leak out” if there
is a hole in the wires.
 The pump of the above hydraulic analogy
model does not need energy to work with.
Activity 5
1. Name the contribution of analogy in
science.
2. What are the limits to analogy?
1. Name the contribution of analogy in
science.
(a) Analogy helps with the development of
new concepts and hypotheses in science
Though the fact that a conclusion inferred
from analogy may be right is due to
probability, analogy is still an important
method to form new concepts especially
during the initial stage of concept or theory
development. In science many important
theories started with some hypotheses
formulated by analogies and then supported
by empirically evidence.
1. Name the contribution of analogy
in science.
 However, new knowledge generated through analogy
must be compared with prior knowledge in order to
have a strong analogical argument. The inferred
properties/ relationship between 2 objects using
analogy method may or may not be true and it all
depends on probability. In general, the relevance of
the similarities is important.
 Moreover, the number of relevant similarities also
matters. The greater the number of relevant and
fundamental properties between the 2 objects, the
stronger the analogical relationship between the two
objects.
 Furthermore, if there are incompatibility between the
inferred properties and the properties of the analogue,
the strength of the analogical inference is weak.
(b) Analogy leads to inventions
The importance of analogy in logic is that
it helps with divergent thinking and
enhances creativity. Many inventions were
due to analogical thinking. For instance, it
was found that bats could fly freely
without hitting any obstacles in the dark.
The discovery of radars was through the
analogy to the sound wave detecting
system of bats.
(c) Analogy provides logical foundation
for modeling experiments
Analogy is commonly used in simulation,
which in turn has been a very important
process in scientific research. For
instance, scientists and engineers
usually use wind tunnels to carry out
investigations on aircrafts.
Wind tunnel
Credit: NASA
2. What are the limits to analogy?
(a) Analogy helps explain science concepts
well but can create misconceptions.
An analogy is sometimes valid for
understanding part of a scientific process but
it may not be able to be applied to the process
as a whole.
(b) The reliability of the conclusion drawn
from analogy depends on empirical evidence.
Supplementary activities:
1. Search for examples of analogies
leading to scientific discoveries or
inventions.
1. Search for examples of analogies
leading to scientific discoveries or
inventions.
 Alexander Graham Bell used analogies to
invent telephones. Bell’s idea for the telephone
was sparked by the human ear structure.
 Scientists tried to use lines to represent lines of
force surrounding a bar magnet.
 The legend that Archimedes (c. 287-212 BC)
used analogy to uncover a fraud against King
Hieron II of Syracuse using his principle of
buoyancy.
2. Challenging Problem
According to a press release dated on 4 June 2008, a
leading microbiologist Professor Yuen Kwok-yung, the
University of Hong Kong, discovered ways to increase the
survival rate of mice infected with H5N1. In the research
mice were first given 1000 times lethal dose of H5N1.
Then after 48 hours one group of mice were given the
antiviral drug, zanamivir while another group of mice was
given the antiviral drug zanamivir and two non-steroidal
anti-inflammatory agents, celecoxib and mesalazine. It was
found that the survival rate of mice infected with lethal
doses of the bird flu virus, H5N1 could increase from 13.3
per cent (zanamivir alone) to 53.3 per cent (i.e. fourfold).
Clinical trials with these three drugs would be carried out
later to investigate the effect on human infected with H5N1.
Discussion Question:
(a) What is the analogy reasoning of
carrying out the clinical trial?
(b) Please comment on the chance of
success of the clinical trial.
(a) What is the analogy reasoning
of carrying out the clinical trial?
 Mice have many similarities to humans.
 Mice infected with H5N1 survive better with
the new treatment (“drug cocktail”).
 Human infected with H5N1 may survive
better with the new treatment (“drug
cocktail”), too.
(b) Please comment on the chance
of success of the clinical trial.
 The experimental data shows that
although the drug cocktail works in
mice, the treatment may not work on
infected human. Mice and human
share many biological similarities but
there are still a lot of biological
differences. It is uncertain that the
drug cocktail works on infected
human.