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| The subtle Tower of Pisa experiment (Cf. discussion here, lab exercise here) |
Physics is the foundational physical science, and (including astronomy) it was at the heart of the scientific revolution from 1543 - 1700 that has so transformed our world.
Physics and allied sciences and fields such as Chemistry, Computer Science [not just Information Technology!], Biology, Engineering/Technology and Mathematics are also at the heart of the ongoing high tech transformation of our world. Logically, then, we of the Caribbean must prioritise effective and widespread, sound education and training in these areas if we are to thrive in the modern world.
At the same time, there is a worrying regional trend in the Caribbean, where such sciences -- and especially Physics -- are seen as "hard" subjects to pass in regional and even international exams, and are shunned.
This is plainly suicidal.
Ironically, decades ago, while I was teaching O level Physics, I learned that, in Russia, at that time [and, maybe, this still continues; I do not know . . . ], EVERY high school student compulsorily did four or five years of Physics and Calculus in High School. So, on the reasonable assumption that the basic genetic deposit of human beings across the world is similar, it is clearly possible to successfully teach such sciences to actually the majority of students.
What can be done? Especially, for the pivotal science, physics?
This issue has been forcibly brought back to my attention by recent requests for interventions with students struggling with physics. Indeed, I have been asked for a proposal, and this is an "open letter" answer. I choose this route, as the problem is plainly regional and needs to be put on our collective front-burner of issues to be dealt with now, if we are to avert predictable and dire consequences. For, if we do not have a critical mass of people in our region with a solid educational achievement base, we are plainly going to be locked out of the high tech economy for the century ahead.
Let us look at this challenge through the lens of second-chance secondary education and its bleed-over into first chance secondary education. In step-wise points of thought:
1 --> There are two main competing systems in our region for doing 14 - 16 year old, High School Physics, the CXC and the Cambridge O Level subject 5054, Physics.
2 --> The latter, on what Cambridge is plainly now saying in general (cf here and here) and in specific, will be there on an ongoing basis, so it is a viable option.
3 --> A particularly attractive feature is that 5054 -- which is internationally recognised -- has two options, a Practical and an Alternative to Practical paper. The former, however, has a School Based Assessment that makes it far less flexible. (I hope that this SBA programme is now well organised with support for sets of exercises and for equipment etc. That was a serious concern when it was introduced in the early 1990's.)
4 --> Practical experience and skills are of course crucial for physics.
5 --> The concepts in physics are extremely abstract, and such need to be built up from an adequate hands-on minds-on basis of activities that interact with physical objects and our physical world, reflected on analytically and quantitatively; through what we can summarise [cf. discussion here] as "the" generic scientific method. I like to sum this up as O, HI PET (Thanks, Pet!):
O -- OBSERVE apparent facts & patterns in nature6 --> A good place to begin is where a good slice of the Scientific Revolution began: with a swinging pendulum, and with experiments with lenses, with falling/rolling objects and basic optical instruments.
H -- HYPOTHESISE: what are the explaining “laws”?
(Here, we try to get at cause-effect links, models and theories that describe & explain patterns in the world.)
I & P -- I & P -- INFER & PREDICT: Based on the suggested “laws,” what will happen in other situations?
ET -- EMPIRICALLY TEST: We try to validate through experiments or observational studies, to see if we can reasonably trust the predictions. (We must always be open to correction: Science is provisional.)
a: Galileo, the key person involved, watched a pendulum in church as a student, and "timed" swings with his pulse; noticing that wider faster swings took more or less the same time as slower, shorter swings. (This holds if the swings are not more than about 6 degrees of arc. [See my short primer for teachers here, thoughts on insightful learning here and my preferred spiral curriculum framework here.])
b: Later on, he experimented with falling objects, and saw that a heavier object and a lighter one [once air resistance was factored out] will fall at pretty much the same rate, contrary to expectations. (With air resistance, there will be a slight delay of a lighter ball of the same size, e.g. wood/steel. Cf. modern exercise using modern technologies and software, here. This makes for a great class sized communal experiment.)
c: Hearing of telescopes -- probably from the Netherlands -- he built his Galilean telescope [with a diverging lens as eyepiece, giving an upright image]; and impressed his city with the commercial possibilities. Making such an instrument is a great, highly instructive and surprisingly do-able exercise:
d: Then, Galileo made a higher magnification [x 30] instrument and looked up at night, making astonishing discoveries about the universe. He also looked at the Sun -- we should NEVER do that, it burns holes in the retina of the eye [this probably contributed to his eventual blindness] -- and saw the phenomenon of sunspots. Instead, project the sun's image to a piece of card held behind a telescope.
e: He was probably aware of the astonishing behaviour of the Camera Obscura, whereby a pinhole in one end of an enclosure creates an inverted image on the opposite side, that can be seen through a translucent screen.
f: Later on, he experimented with heavy balls rolling in polished troughs and saw that if you have a U-shaped trough, the ball tends to rise to the original level. So he did a thought exercise: what if you made a perfectly smooth trough and then did not ever bring back up the far arm of the U? Would not the ball roll on forever . . . a form of the First Law of Motion: the principle of inertia by which what is at rest remains that way unless disturbed, and what is moving tends to keep its same motion going unless disturbed.
g: Similar exercises with inclined troughs point to the relationship between force and acceleration summed up in the Second Law of Motion: force is proportional to acceleration for the same mass.
h: Flicking one marble on a flat trough into another of the same mass will lead to the first stopping dead and the second heading off at the same speed. This points to the Third Law of Motion: when two bodies interact the forces of action and reaction are equal in size and opposite in direction.
(A great analysis exercise is of how we walk by pushing back on earth [50 -100 kg vs 6 * 10^24 kg], then how a car, a motor boat, a propeller aircraft, a jet plane, a rocket and a helicopter move.)
7 --> Such exercises, with aid of video cameras [= cell phones!] and computer based analysis [laptops are now common and there is some good open source software], done as class exercises, can help build up a powerful physical intuition, based on concrete experience. With appropriate USB input device and software, a Laptop is a good digital oscilloscope, too; go for one good unit for demonstrations and serious investigations, cf. the Picotech range (catalogue here). (I would also invest in a set of low-cost Digital Scopemeters -- the Velleman 140i 10 MHz b/w, 40 MSa/s single i/p channel unit from Jameco is US$209 ea, $ 189.95 for 5+.)
8 --> Such class-sized exercises should of course be backed up by small group or even individual exercises, and this can then be multiplied by exposure to videos, animations, thought exercises and the like, helping to build up experience with physical objects, instruments, tools etc, as well as the process of experimental investigation and theoretical analysis. Having a concrete feel for how things are and how investigations are done, makes a big, rich impact.
9 --> One very important individual or group exercise would be to go out on a clear night and take a visual survey of the skies, especially at the time of year, month and/or night when the Milky Way is visible. That way, students can orient our solar system in our galaxy, noticing the galactic centre in Sagittarius just north of the Scorpion [fish-hook and fan of stars] , seeing the dust lanes, and perhaps picking out some of the key constellations. Learning how to use the Big Dipper to pick out Polaris, the pole star is an especially useful exercise.
10 --> A discussion of the Celestial Sphere, its connexions to our system of latitude, time zones, and longitude, and to the layout of our solar system and sky, would also be eye-opening. One could even do a crude shooting of the sun angle exercise, and comparison with Greenwich time, to estimate longitude. [Cf. my survey here on.]
11 --> This brings up the subject of class demonstration kits, and individual lab exercise kits. I suggest that, for class communal exercises, we could look at something like the PK-S Lab Pack by Labpaq as a class level kit, US$ 180 or so, with 24 exercises. the ideas discussed here for design of exercises by taking advantage of things like camera equipped cell phones and PCs for analysis, and even for timing on sounds, are rich with suggestions.
12 --> For small group exercises, I suggest something like the physics set (similar to a chemistry set) here; for more mechanical topics. For optics, Edmund Scientific has long held sway, and it offers the classic OSA Optics Discovery Kit for less than US$ 20 each. For electricity and electronics, I think an experiment workstation such as these by Elenco [Snap Circuits as a class demo kit for those less comfortable with electronics], or Elenco's XK 150 Analogue/Digital electronics trainer station [cf. here] or even Radio Shack [cf here], will likely work well. I would suggest that maybe a half dozen or a dozen sets may be useful for typical group sizes. Of course, if you have the budget, you may go for a more conventional lab setup, which will be more robust.
13 --> For wave motion, after the classic slinky [directly demonstrates transverse and longitudinal waves], I strongly believe in a ripple tank used with an overhead projector. Unfortunately they are expensive and require what is now specialised and rare equipment, the overhead projector. As an introduction, I would use a pyrex dish to show ripples and how they move, then use a YouTube video, and some software simulations. Propagation, interference, diffraction, refraction, reflection etc can all be demonstrated and made sense of, leading to the Huygens construction approach to understanding waves.
14 --> Beyond that, for optical waves, I would experiment with the laser pointer, with due precautions being taken. The classic speed of sound by clapping blocks and synchronising echoes is a great, instructive class exercise, too.
15 --> Molecular and atomic topics are perhaps best approached by using marbles in action in a tray type demonstrations, and by using electricity and maganetism as gateway foci, e.g. showing how a magnet behaves, and a solenoid, leading to what is magnetism, charge and current? From that the sun and planets model of an atom and ball-stick models of molecules can then lead to many of the onward themes. The classic exercise of a drop of oil on a dish of water displacing a powder, can give the scale we are dealing with by estimating the thickness of a monomolecular layer disk of oil. I would go for video as at least a visual way to conceive of the atom and the physics of its constituent parts.
16 --> It should be clear that I am emphasising practical exposure as the foundation for forming insightful, accurate concepts and acquiring the science as a meaningful system of thought. It is in this context, that I would bring in the theoretical expositions, and associated mathematical techniques. Problem exercises would then be introduced as pencil and paper or thought exercise versions of what could be done practically if we had the time.
17 --> In terms of structure, 5054 has six main sections:
I: General Physics
II: Newtonian Mechanics
III: Energy and Thermal Physics
IV: Waves
V: Electricity and Magnetism
VI: Atomic Physics
18 --> This broadly reflects the historical and conceptual development of the discipline. It can fit with a five or six-term structure, with half a term per main module. I would push in a bit of optics and lenses, for the experimental value. (I normally would cluster General Physics and Newtonian Physics.)
19 --> In a revision/second chance course, I would follow essentially the same framework, using lab demonstrations and guided discussion to spark integration of concepts, led on to problem solutions.
20 --> I would also use the syllabus as a revision aid, by making students finish the "Student Will/Should Be Able to . . . " as a prompt for testing and building up recall of key points. Past paper exercises will be helpful as integrative revision also. [When reviewing topics, I would focus on textbook type exercises, then shift to exam review with the past papers.]
21 --> To eliminate hassles [albeit, in a school, doing practicals year by year is a handy way to build up apparatus!], I would use the alternative to practical paper. Student experience and confidence with practical exercises and analysis should make this "easy meat."
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The point here is to build in a foundational level of achievement in a key discipline. Other bridging studies and onward courses would then lead to the Associate degree level. This level is the strategic pivot for regional educational transformation. END
PS: For reference, I suggest Motion Mountain.
PS: For reference, I suggest Motion Mountain.
