IoP Energy: Once More Unto The Breach…

Why do we make these analogies? It is not just to co-opt words but to co-opt their inferential machinery. Some deductions that apply to motion and space also apply nicely to possession, circumstances and time. That allows the deductive machinery for space to be borrowed for reasoning about other subjects. […] The mind couches abstract concepts in concrete terms.

— Steven Pinker, How The Mind Works, p.353 [emphasis added]

I am, I must confess, a great believer in the power of analogy.

Although an analogy is, in the end, only an analogy and must not be confused with the thing itself, it can be helpful.

As Steven Pinker notes above, the great thing about concrete analogies and models of abstract concepts is that they allow us to co-opt the inferential machinery of well-understood, concrete concepts and apply them to abstract phenomena: for example, we often treat time as if it were space (“We’re moving into spring”, “Christmas will soon be here”, and so on).

To that end, I propose introducing the energy stores and pathways of the IoP model to KS3 and GCSE students as tanks and taps.

Energy Stores = tanks

Energy Pathways = taps

Tank and taps

Consider the winding up of an elastic band.

tank and taps 3

This could be introduced to students as follows:

tank and taps 2.PNG

One advantage I think this has over one of my previous efforts is that I am not inventing new objects with arbitrary properties; rather, I am using familiar objects in the hope of co-opting their inferential machinery.

Suggestions, comments and criticisms are always welcome.

My propositions are elucidatory in this way: he who understands me finally recognises them as senseless, when he has climbed out through them, on them, over them. (He must so to speak throw away the ladder, after he has climbed up on it.)

He must surmount these propositions; then he sees the world rightly.

— Ludwig Wittgenstein, Tractatus Logico-Philosophicus (1922), 6.54

 

 

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IoP Energy: It’s About The Physics, Stupid!

[I]t is ambition enough to be employed as an under-labourer in clearing the ground a little, and removing some of the rubbish that lies in the way to knowledge;- which certainly had been very much more advanced in the world, if the endeavours of ingenious and industrious men had not been much cumbered with the learned but frivolous use of uncouth, affected, or unintelligible terms, introduced into the sciences

John Locke, An Essay Concerning Human Understanding (1690)

OK, so I was wrong.

In a previous blog, I suggested a possible “diagrammatic” way of teaching energy at GCSE which I thought was in line with the new IoP approach. Thanks to a number of frank (but always cordial!) discussions with a number of people — and after a fair bit of denial on my part — I have reluctantly reached the conclusion that I was barking up the wrong diagrammatic tree.

enoji19

The problem, I think, is that unconsciously I was too caught up in the old ways of thinking about energy. I saw implementing the new IoP approach as being primarily about merely transferring (if you’ll pardon the pun) the vocabulary. “Kinetic store” instead of “kinetic energy”? Check. “Gravity store” instead of “gravitational potential energy”? Check. “Radiation-pathway-thingy” instead of “light energy”? Check.

Let’s look at the common example of a light bulb and I will try to explain.

Using the old school energy transfer paradigm, we might draw the following:

enoji20

In spite of its comforting familiarity, however, there are problems with this: in what way does it advance our scientific understanding beyond the bare statement “electricity supplied to the bulb produces light and heat”. Does adding the word “energy” make it more scientific?

For example, when we are considering “light energy”, are we talking about the energy radiated as visible light or the total energy emitted as electromagnetic waves? It is unclear. When we are considering “heat energy” are we talking about the energy emitted as infrared rays or the increase in the internal energy of the bulb and its immediate surroundings? Again, it is unclear.  In the end, explanations of this stripe are all-too-similar to that of Moliere’s doctors in The Imaginary Invalid, who explained that the sleep-inducing properties of opium were due to its “dormative virtues”; that is to say, sleep was induced by its sleep-inducing properties.

The problem with the energy transfer paradigm is that it draws a veil over the natural world, but it is a veil that obscures rather than simplifies.

The IoP, after much debate, collectively rolled up its sleeves and decided that it was time to take out the trash. In other words, they wanted to remove the encumbrance of terms that had, over time, essentially become unintelligible.

The new IoP model distinguishes between stores and pathways. For example, an object lifted above ground level is a gravity store because the energy is potentially available to do work. Pathways, on the other hand, are a means of transferring energy rather than storing energy. For example, the light emitted by a bulb is not available to do work in the same sense as the energy of a lifted weight. It is, within the limits of the room containing the bulb, a transient phenomenon. Many photons will be absorbed by the surfaces within the room; a small proportion of photons will escape through the window and embark on a journey to Proxima Centauri or beyond, perhaps.

Now let’s look at my well-meaning diagrammatic version of the energy transfers associated with a light bulb:

pathway-bulb

The stores are “leak-proof buckets” holding the “orange liquid” that represents energy. The pathways are “leaky containers” that enable energy to be transferred from one store to another. I have to admit, I was quite taken with the idea.

The first criticism that gave me pause for thought was the question: why mention the thermal store of the bulb? Surely that’s a transient phenomenon that does not add to our understanding of the situation. Switch off the electric current and how long would the thermal store be significant? Wouldn’t it be better to limit the discussion to two snapshots at the beginning (electrical pathway in) and end (radiative pathway out)?

The second question was: what does the orange liquid in the pathways represent? In my mind, I thought that the level might represent the rate of transfer of energy. Perhaps a high power transfer could be represented by a nearly full pathway, a low power transfer by a lower level.

But this led to what I thought was the most devastating criticism: why invent objects and assign clever (but essentially arbitrary) rules about the way they interact when you could be talking about real Physics instead?

Is there any extra information in the phrase “light energy” as opposed to simply the word “light”?

Blackbody2

Efficiency of a bulb: find the total energy emitted as visible light and divide by the total energy emitted as light of all wavelengths.

And that’s when I realised that I wasn’t helping to take out the trash; in fact, I was leaving the rubbish in place and merely spray painting it orange.

Now don’t get me wrong, I think there’s still a long road ahead of us before we become as comfortable with the IoP Energy newspeak as we were with the old paradigm. As a first step, I suggest all those interested should read and contribute to Alex Weatherall’s excellent Google doc summary to be found here. But I honestly believe that it’s a journey worth taking.

Opium facit dormire.
A quoi respondeo,
Quia est in eo
Vertus dormitiva

— Moliere, The Imaginary Invalid (1673)

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IoP Energy: Notes Towards A Diagrammatic Teaching Approach?

After a fascinating discussion led by the excellent Alex Weatherall (click here to participate in his Google doc Physics-fest — and follow @A_Weatherall on Twitter for more), I was thinking on possible teaching approaches for energy.

Although I think the IoP‘s (the UK’s Institute of Physics) approach is conceptually sound (see previous post here) and addresses many of the shortcomings in the traditional and time-hallowed “forms of energy” approach, many Physics teachers (myself included) are struggling to find direct and simple ways of communicating the highly nuanced content to students.

For example, to describe a filament bulb:

A (filament) light bulb is a device that takes energy in (input) through an electrical pathway (the current) to the thermal energy store of the filament (the metal is getting hotter) which transfers the energy through the radiation pathways of light (visible and IR). There is an increase in the thermal store of the room due to transfer via the heating pathway. The less energy transferred by heating compared to visible light the more efficient the light bulb.

I think this is in accordance with the letter and spirit of the “IoP Energy Newspeak” approach; but sadly, I can picture many students struggling to understand this, even though it was written by many hands (including mine) with the best of intentions.

But then I began to think of adopting a diagrammatic “enoji” approach. (See here for suggested energy icons, or energy + emoji = enoji)

 

Diagrams for Stores and Pathways

An energy store is represented by a “watertight” container. For example, the gravity store of a ball at the top of a slope could be represented thus:

gravity-store

Because it is an energy store, the amount of energy (represented by the level of orange liquid) in the store remains constant. Energy will not spontaneously leave the store. Energy stores don’t have holes. The unit we use with energy stores is the joule.

However, energy pathways do have holes. In contrast to an energy store, the energy level in a pathway will spontaneously decrease as the energy is shifted to another store.

pathway

To keep the energy level constant in a pathway, it needs to be constantly “topped up” by the energy from an energy store.

Since a pathway represents a “flow” of energy, the unit we use with an energy pathway is the watt (one joule per second). The “orange liquid level” in the pathway icon could therefore represent the amount of energy flowing through in one second (although I concede that this idea, though promising, needs more thought).

 

“Enoji Energy Shift” Diagrams

Adopting this convention, the “enoji energy shift” diagram for a ball rolling down a slope might look like this:

pathway2

An energy store does not have any holes — unless it is linked to a pathway, like the gravity store above. Energy will move in the direction indicated by the energy pathway icon.

Simplified in a student exercise book, it could be represented like this:

simplepathway1

The small upward and downward arrows are an attempt to indicate what happens to the energy level over time.

 

The Filament Lightbulb “Enoji Energy Shift” Diagram

This could be represented in a student exercise book like this:

pathway-bulb

Since there are no small up and down arrows on the pathway or thermal store enojis, this indicates that the energy levels are relatively stable (provided we have a constant input of energy from the power station). However, the energy level of the thermal store of the surroundings just keeps on going up…

 

And finally…

Please note this is a work in progress.

I fully expect many teachers will think that the suggested set of conventions may well prove more confusing for students.

However, what I am attempting to do is to give students a set of simple, coherent yet serviceable analogies. In other words, this might provide a conceptual “tool kit” of physical representations of very abstract processes involving energy.

I hope readers will agree that it offers some scope for further development. Comments, criticisms and suggestions would be most welcome.

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Brownian Motion, Staff Rooms and Bromeliads

Individuals aren’t naturally paid-up members of the human race, except biologically. They need to be bounced around by the Brownian motion of society, which is a mechanism by which human beings constantly remind one another that they are…well…human beings.

— Terry Pratchett, Men At Arms

Happiness is . . . not having an office.

I had a job once where I had an office. It was a quite a nice office. And I had it all to myself. It was a quiet, pleasant little space with a small kitchen nearby. It even had natural daylight through a large window Perfect, you might think.

But I grew to hate that office. You see, I think that teachers — more than anyone, perhaps — need, occasionally, to be “bounced around by the Brownian motion of society”. 

What is Brownian motion? Well, it was first observed by botanist Robert Brown in 1827, who noted that, under a microscope, pollen grains in water seemed to “jiggle” randomly. Brown at first assumed that this motion was due to the “life force” of the pollen grains; however, he dispensed with this idea when he saw particles of stone dust (reportedly taken from the Great Pyramid to make sure they were completely and utterly devoid of life) perform the same drunken, wiggly waltz that came to be known as Brownian motion.

And there the matter rested, for a while. And then in 1905, a young patents clerk, working in his spare time at a kitchen table in a very modest apartment in Geneva, suddenly discovered the explanation — and more, much more.

The patents clerk’s name was, of course, Albert Einstein. His explanation rested on the insight that the visible pollen or dust particles were being buffeted by invisible water particles. His mathematical analysis was not only the first verifiable evidence of the actual physical existence of atoms, but also established their size. Understanding the movement and nature of the unobservable by minute and careful scrutiny of the observable…

Looking back at the job with its own office, I think I missed the simple daily dose of teacherly Brownian motion that you get by simply stepping into a staff room. Are you a little too-full-of-yourself-by-half? Some friendly ego-puncturing banter is usually on tap. At your wit’s end with a difficult student or class? A sympathetic shared eye-roll can work wonders. Plus there might even a few good ideas thrown in for good measure.

A good school staff room is not always synonymous with a “good” school, but a good staff room can make even a “bad” school bearable — enjoyable, even! — and the lack of one can make even an “outstanding” school feel like a souless and joyless treadmill.

If you are being interviewed by more than one school, choose the one that has the beat-up, well-used furniture in the staff room, replete with dirty coffee mugs and tottering piles of unmarked marking whose lower layers are being spontaneously formed into sedimentary rock by the crushing pressure from above.

Sadly, I feel that that this type of staff room is a vanishing phenomenon. I suppose that I am like a dinosaur complaining that bromeliads these days don’t taste as nice as the bromeliads they had in the old days.

Teachers today just aren’t rubbing elbows as much as they used too. H’mmm. Maybe that’s why we don’t have to wear elbow patches any more…

But that does not detract from this universal truth that should, I feel, be more universally acknowledged: if a staff room is suspiciously neat and clean and looks like an airport lounge…RUN AWAY!

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A Classicist Writes

My lovely wife Laurie has started her own blog called A Classicist Writes.

She writes on Ancient Greece and Rome (she has an M.A. in Classical Studies), cats, Ralph Waldo Emerson, more cats, more Ralph Waldo Emerson, and other topics.

Hope you enjoy!

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Look at the pretty pictures…

Uniformity of practice seldom continues long without good reason.

So opined the estimable Dr Johnson in 1775. In other words, if a thing is done in a certain way, and continues to be done in that same way for a number of years by many different people, then it is a pretty safe bet that there is a good reason for doing the thing that way. And this is true even when that reason is not immediately apparent.

For the choice of this situation there must have been some general reason, which the change of manners has left in obscurity.

— Samuel Johnson, A Journey To The Western Islands of Scotland (1775).

Consider the following examples of “uniformity of practice”:

wp-1487108711715.png

wp-1487109018433.pngexam1

They are fairly bog-standard GCSE examination questions from the last two years from three different exam boards. But compare and contrast with an O-level Physics paper from 1966:

exam2.jpg

exam3.jpg

 

The “uniformity of practice” that leaps out at me is that the more modern papers, as a rule, have many more illustrations than the older paper. Partly, of course, this is to do with technology. It would have been (presumably) vastly more expensive to include illustrations in the 1966 paper.

Even if we assume that the difficulty level of the questions in the modern and older papers are equivalent (and therein lies a really complex argument which I’m not going to get into), there is a vast difference in the norms of presentation. For example, the modern papers seems to eschew large blocks of dense, descriptive text; this extends to presenting the contextual information in the ultrasound question as a labelled diagram.

Now I’m not saying that this is automatically a good or a bad thing, but there does seem to be a notable “uniformity of practice” in the modern papers.

Now what could the “general reason” for this choice?

Rather than leave the “change of manners” responsible for the choice “in obscurity”, I will hazard a guess: the examiners know or suspect that many of their candidates will struggle with reading technical prose at GCSE level, and wish to provide visual cues in order for students to play “guess the context” games.

Now I’m not assigning blame or opprobrium on to the examiners here. If I was asked to design an exam paper for a wide range of abilities I might very well come up with a similar format myself.

But does it matter? Are we testing Physics or reading comprehension here?

My point would be that there can be an elegance and beauty in even the most arid scientific prose. At its best, scientific prose communicates complex ideas simply, accurately and concisely. It may seem sparse and dry at first glance, but that is only because it is designed to be efficient — irrelevancies have been ruthlessly excised. Specialised technical terms are used liberally, of course, but this is only because they serve to simplify rather than complicate the means of expression. 

Sometimes, “everyday language” serves to make communication less direct by reason of vagueness, ambivalence or circumlocution. You might care to read (say) one of Ernest Rutherford’s papers to see what I mean by good scientific prose.

The O-level paper provides, I think, a “beginner’s guide” to the world of scientific, technical prose. Whereas a modern question on falling objects might tack on the sentence “You may ignore the effects of air resistance” as an afterthought or caveat, the O-level paper uses the more concise phrase “a body falling freely” which includes that very concept.

To sum up, my concern is that in seeking to make things easier, we have actually ended up making things harder, and robbing students of an opportunity to experience clear, concise scientific communication.

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The Gamesters of Sparta

Sir. It must be considered, that a man who only does what every one of the society to which he belongs would do, is not a dishonest man. In the republick of Sparta, it was agreed, that stealing was not dishonourable, if not discovered.

— Samuel Johnson

At a recent event, the speaker asked us to consider a hypothetical conundrum: what if one GCSE Triple Science student was strong in (say) Chemistry and Biology, but significantly weaker in GCSE Physics? 

What course of action would you recommend? Extra support in Physics, was the consensus reply. 

Actually, said the speaker, the smart “Progress 8 Maximisation Strategy” would be to:

  1. Tell the student to focus her efforts entirely on Biology and Chemistry and completely ignore Physics. . .
  2. . . . but keep her entered for GCSE Physics anyway, and make sure that she goes into the exam hall and writes her name on the Physics papers, even if she does nothing else.

That way, she has ostensibly followed a full and balanced curriculum. She has, after all, been entered for all three Science subjects.  And, since Progress 8 counts only the two highest Science grades (or so I’m told), the student’s contribution to the school’s league table position would be also be secure.

H’mm. Dishonest? No. In the school’s best interests? Definitely. In the student’s best interests? Erm . . . on balance, no.

Sadly, as the character Joseph Sisko (ably played by Brock Peters) once observed on Star Trek: Deep Space Nine: “There isn’t a test that’s been created that a smart man can’t find his way around!” And that includes Progress 8 . . .

Sir, I do not call a gamester a dishonest man; but I call him an unsocial man, an unprofitable man. Gaming is a mode of transferring property without producing any intermediate good. 

— Samuel Johnson

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