Tuesday, June 13, 2017

Science Education Hamstrung By Dubious Laws & Flawed Intuitive Ideas

Let's face it, learning even basic concepts for physics and astronomy does not come naturally for most people. Even teachers!  I discovered this while giving the first teacher workshops in the teaching of astronomy for the Caribbean, back in 1978.   Among the beliefs I encountered among these teachers who were to devote themselves to the first ever serious secondary school astronomy syllabus :

- The stars were merely pinprick size holes in a vast dome called the night sky

-  The Sun was not a star but totally different, real stars were tiny bright points

-   The Sun went around the Earth not the other way

-   The Moon had to be the same size as the Sun to cause solar eclipses

Each of these, in fact, can be traced to the person's intuition or what the cognitive scientist Andrew Shtulman calls "intuitive theories". In other words, misbegotten notions of how the world or universe works based on internalizing goofy ideas that seem right but aren't.

Of course, it's no different with physics. Millions still accept or believe that heavier objects must fall to the Earth faster than lighter ones. This despite the fact that it's been experimentally demonstrated since the time of Galileo that all object fall at the exact same rate, once air resistance is corrected for.

Others believe firmly in an "impetus" kind of motion originating with some kind of imaginary force that fades over time, despite the fact that Newtonian physics allows no such "force.

Then there are those who are certain that linear transfer of momentum is a myth, so that when they see Jackie Kennedy in the Zapruder film moving back over the limo trunk to try to retrieve a dislodged occipital bone from JFK's head, e.g.
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They still are unable to process the shot had to have come from the front. A bullet fired from the rear hitting the back of Kennedy's head could not possibly drive it back toward the rear shooter because the linear momentum imparted is not in that direction.  A rear shot instead would drive the head forward and its content out front. Basic stuff, but it still boggles minds.

To demonstrate the principle of linear momentum transfer in a lab setting is fairly straightforward, making use of an air track, of the type used to measure accelerations, e.g.

In the case of momentum transfer we ensure the track is level so there is no extraneous acceleration from gravity and place a stationary trolley on one side while sending the other in motion from the opposite side. The student who performs the lab will see the moving trolley strike the stationary one (we assume both of the same mass) and then both move off in the same direction, i.e. the direction of the moving trolley. (N.B. there is no 'rubber' bumper on the stationary trolley).

Millions more are equally befuddled by the idea that forces always occur in pairs, so a book (A) resting on the table (B) - exerting the force of its weight F(AB), must have the table also exerting a force on it (F(BA).
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This is an application of Newton’s 3rd law which states that “for every action (force) there is an equal but opposite reaction (counter force).

All of which informs us that it isn't sufficient to rely on our intuition of a physical system to understand what is going on.  That intuitive picture, alas, is generally flawed.  The success of science education, then, lies in eliminating as many flawed intuitive ideas as possible and replacing them with correct scientific principles.

In physics, at least, this is relatively straightforward to do by way of experiments, i.e. dropping objects from a set up such as shown below - connected to an electronic timer which imparts dots on tape that can then be compared with the accelerations computed..

One can then check to see that a 5 g mass and 20 g mass fall at the same rate, hence have the same accelerations subject to  the Earth's gravity.

With the proper equipment other experiments can also be devised, say to test the principle of linear momentum transfer, or that heat is transferred from hotter to cooler bodies. 

In terms of the astronomy misconceptions already cited, while it is not possible to perform actual experiments, it is feasible to use models to high light false thinking. For example, using two balls of very different size - say one a 1 cm marble, the other a softball of 9.65 cm diameter, to represent the Sun and Moon. Then by placing the former much nearer to the observer's eyes and the latter much further away, it can be shown how the marble (representing the Moon) can exactly block out the larger (Sun).  All that's needed is getting the right distance to the observer for each to produce the "block out" effect (similar to what happens in a total eclipse. Most importantly the Moon needn't ne the same size as the Sun - only the same angular size (e.g.1/2 degree or 30 arcmin) when the eclipse occurs.

Similar techniques using light sources can be used to show - in a model situation - that the Sun is a star, and only appears much different (and brighter) because it is so much closer to Earth than other stars.  Place a bright torch or flashlight within 1 meter of an observer - say to show the "Sun" from Earth, then change the distance to 100 m (needing a large field - preferably at night) to see just a tiny point of light. The light source is the same, it's just observed from radically differing distances. The same applies to the Sun and other stars, they only appear to be different entities because the Sun is observed much closer than the other stars.

While the challenge of dismissing false ideas is significant, the science educator also faces spurious "first amendment" arguments by state legislators, trying to dignify pseudo science in evolution and climate science. For example,  in South Dakota, supporters of SB 55 claimed the bill was necessary to "protect the academic freedom and free speech rights of teachers". A challenge by the National Committee Against Censorship (NCAC) pointed out that while teachers have the right to their own opinions they do not have any First Amendment right "to deviate from and possibly contradict professionally developed science standards adopted by state educators".   The argument led to the defeat of the bill.

Similarly, in Oklahoma, an anti-evolution legislator proposed a bill that would allow teachers to present alternatives to evolution such as creationism. Of course, creationism is not science in any manner, shape or form it is religious doctrine.  It is simply gussied up with scientific seeming terms. Creationists don't even provide their own tests for falsifying their own alleged theories! For example, the evolutionist provides a falsification test for his theory of common descent (i.e. that both Man and apes are descended from the same common ancestor) by using the cytochrome-c sequence, say as disclosed in chimps and humans, and asserting that beyond a certain (probability)  threshold the test fails.

This OK bill is now also under challenge by the NCAC.  Because of these contentious legal issues and states unwilling to accept standard science, Andrew Shtulman, in his book SceinceBlind, suggest evolutionary concepts need to be taught before high school using graspable charts.  E.g.

Diagram showing the putative evolution of late Devonian fish.

Let's agree it is by no means easy to dispel flawed notions of science based on intuition or religious belief, not to mention those interjected via misplaced state laws. The educator needs to realize it's a ceaseless struggle.  Research shows that even general lessons in critical thinking do not measurably improve performance on science tests. (Mostly because too many such tests are still based on content).  But never mind, they are still useful for engendering a citizenry capable of applying skepticism  to pseudo-scientific claims - especially the type that bombard us each and every day.

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