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Enhancing Thinking Skills in Science Context Lesson 8 Analogies in Science.

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1 Enhancing Thinking Skills in Science Context Lesson 8 Analogies in Science

2 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)?

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4 The piece of paper is folded to a ring-shaped structure.

5 The ring-shaped paper roll acts like a pillar (an example of analogy) and can support heavy weights.

6 The piece of paper is folded to a cylindrical - shaped structure.

7 This cylindrical paper roll acts like a pillar (an example of analogy) and can support heavy weights, too.

8 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 ) 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.

9 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?

10 What can a scallion do?

11  In what way(s) are urinary tracts and scallions in common? Shape? Property /function?

12 What can a scallion do? pen string Hair band straw shoelace Vine basket

13  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.

14 Discussion questions: Urinary tracts and scallions are similar. Dr. Sun used analogy to find a solution to the problem of his patient.

15 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.

16 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.

17 Analogy A: X1, X2, X3, …… ; W B: X1, X2, X3, …… Therefore, B may have property W.

18 Relationship among analogy, induction and deduction in science Generalisation Special attribute A (particular facts or ideas) Special attribute B (particular facts or ideas) InductionDeduction Analogy (reference: 《類比》王溢然,張耀久 (2001))

19 Activity 3 Below is the data of two solar system objects, the Earth and the Mars:

20 Special featuresEarth Mars ( 火星 ) Shapespherical Moonone moon2 moons Orbital period1 earth year 1.9 earth year (remarks: Neptune-164 earth year; Uranus-84 earth year)

21 Surface temperature Average 17 degree Celsius -93 to -3 degree Celsius Average density5500 kg/m kg/m 3 Surface gravity1.00 (Earth= 1.00) 0.38 Atmospheric pressure 1.0 (Earth = 1.00) 0.007

22 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 WaterAbundant amount of water In 2007 scientists discovered that the south pole of Mars was covered by dry ice and cold water. MethaneReleased as metabolites of living organisms The presence of methane was detected in 2003.

23 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.

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25 Task 1 1.Fill in the blanks: Wires  () Potential  () Voltage (potential difference)  () Current  () Resistor  () Reference website (analogy model): rent/WaterFlowAnalog.html

26 Hydraulic analogy to explain electric circuit Wires Electrical Potential Voltage Electric current Light bulb Pump Water pipes Water pressure Paddle Difference in pressure between two points Water current Dry cell

27 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.

28 Activity 5 1.Name the contribution of analogy in science. 2. What are the limits to analogy?

29 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.

30 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.

31 (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.

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34 (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.

35 Wind tunnel Credit: NASA

36 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.

37 Supplementary activities: 1. Search for examples of analogies leading to scientific discoveries or inventions.

38  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 BC) used analogy to uncover a fraud against King Hieron II of Syracuse using his principle of buoyancy.

39 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.

40 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.

41 (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.

42 (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.


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