Uncategorized

Listen to Keano: write only what the examiner wants to read

Back in 2013 Manchester United played Real Madrid in a Champions League match.
In the 56th minute Nani went into a tackle with his foot up high; the referee not only gave a free kick against United – he also sent Nani off.
United lost the game and as a result went out of the competition.

Afterwards the ITV commentary team were discussing whether or not the referee made the correct call. They replayed a clip of the action at normal speed, then in slow motion.
Roy Keane was on the panel but wasn’t saying much at this stage. Finally the host asked him what he thought. It’s very simple he said; the debate here shouldn’t be about whether or not the referee made the correct call – the discussion should be why Nani was daft enough to raise his leg that high in the first place. By doing so he was creating a situation where the referee was forced into making a call one way or the other. At that stage the damage was done. Nani should have known better.

Whenever I correct a test I usually get a couple of answers where it’s unclear whether or not they merit full marks.
My tendency now is not to award the marks. This highlights to the student the danger of putting the examiner in a situation akin to the referee in the story above.

And Keane’s point is just as applicable here – If at all possible avoid creating a situation where the examiner has to make a call as to whether or not to give you full marks. It may seem obvious, but if it’s the leaving cert then remember that you won’t be in the examiner’s house when he’s correcting your paper, so you won’t have the opportunity to explain to him (or her) what you meant by your answer. And even though your answer may make perfect sense to you, it may still not get full marks on the day.

The moral of the story? Give onto the examiner that which is his. If there is a standard answer to a commonly-asked question then just learn it. And make sure that this answer – and only this answer – is what you write down on the day of the exam. If you’re reading this as a parent then check that your child knows their definitions – and if they stray off course by putting things in their own words then don’t be afraid to give them a red card.
On a serious note, if their definition doesn’t make sense to you (if it doesn’t read as an english sentence should) then it probably won’t make sense to an examiner either.

As I mentioned in my last post this is all just a game.
And this is just one of the rules.
So if you want to play you have to learn the rules.
Make Keano proud.

 

This was the closest I could get to a video of the discussion. Unfortunately it kicks in just after Keane’s comment about Nani unnecessarily putting the referee in a situation where he had to make a judgement call.
But then again, Keane is always worth watching.

For what it’s worth, the clip also illustrates one of our inbuilt biases known in psychology as fundamental attribution error. It’s one of the most profound ideas in all of science because it tells us that our own view of reality is filtered in such a way as to make us seem to be better than we actually are. But maybe that’s for another day.

Irish company Havok makes waves with its Physics engine

Havok is an Irish company.
This gives us a pretty good idea of what they are about:

Take a look at their leadership team to see the interdisciplinary nature of their combined skillset.
Havok make the news recently and the following was posted on an american physics-teachers’ forum.
I am reposting it here with permission from the poster – John Denker:

Here is a news report that mentions physics in a real-world context:
http://techreport.com/news/29142/microsoft-acquires-havok-physics-engine-from-intel

Every video game has a module called the “physics engine”.
A good physics engine is worth a bunch of money.
The price that Microsoft paid has not been announced, but I reckon it is in the neighborhood of a billion dollars. That’s based on the fact that Intel paid 110 million to acquire Havok back in 2007.

This is useful as part of the answer when students ask what physics is good for in the real world. The number of physics jobs in the computer graphics industry is not super-huge, but it’s more than the number of physics jobs at (say) CERN.

It’s also worth mentioning that most of the high-paying jobs are interdisciplinary. Expertise in physics alone is not nearly so valuable as expertise in physics /and something else/. Even more valuable is the skill we call life-long learning, i.e. being able to come up to speed in a new area quickly.

Let’s remove voltage from the Junior Science syllabus; post #1

 

Dear Mr/Ms Junior Cert Syllabus writer,

The time has come to question why the concept of voltage is still on the Junior Cert syllabus.
It is by far the most difficult concept for students (and indeed teachers) to grasp.
Consider a relevant extract from the Junior Cert Science syllabus

Set up a simple electric circuit, use appropriate instruments to measure current, potential difference (voltage) and resistance, and establish the relationship between them

Let’s take a look at potential difference (commonly referred to as ‘voltage’):

The following extract has been taken from the minutes of a History of Science meeting, in 2002.

John Roche, of Linacre College, Oxford, opened the session after tea, speaking on the concept of voltage. He began by claiming that almost every concept in electricity and electromagnetism is ambiguous, and the concept of voltage is one of the most incoherent. Its evolution is difficult to follow.

 Abbé Nollet, in the 18th century, distinguished quantity and degree of electrification. Others made similar distinctions between quantity and intensity or tension or pressure – what we would call voltage.

 Roche showed how the term “voltage” had come to be used nowadays in three different ways; for electromotive force, potential difference and (absolute) potential.

Volta defined electrical tension as the endeavour of the electrical fluid to escape from a body. Volta’s tension was more akin to a force, unlike the modern definition of electromotive force, which is a misnomer, being defined in terms of energy.

Ohm carried Volta’s concept to closed circuits with the idea that voltage was proportional to the difference in tension between the ends of a conductor. For Ohm, it was the gradient of electrical tension that drove the current.

Poisson introduced an entirely different concept, of charge divided by distance to a point, which Green called the potential. This was an analytical device only, arising from an analogy with Laplace’s gravitational potential function.

Kirchhoff reconciled Volta’s tension with Poisson’s potential function through the concept of energy or vis viva introduced by Helmholtz. From Kirchhoff, current is driven by the electric field in a conductor and voltage is related to the energy supplied, but physicists and electrical engineers do not usually think of them in this way.

All the earlier interpretations remain current, but with different weights, and most of the time voltage is seen as a driving energy.

 IOP History of Physics Group Newsletter, Spring 2000, page 65

So what exactly should we be telling our students about potential difference? How many (non-physicist) science teachers can define or explain potential difference? Maybe most can, but if so I would be very pleasantly surprised.

Would it hurt anyone if we replaced the syllabus extract above with something more simple, like the following?

Set up a simple electric circuit using appropriate instruments to light a number of bulbs in series.
Understand that for current to flow a power supply and a complete circuit are required.

The other aspects of the syllabus on electricity could remain as they are, but no Ohm’s Law, no experiment to verify Ohm’s Law, no mathematical problems based on Ohm’s Law, and no more mention of potential difference.

Let’s put the swine flu in perspective

The total number of deaths in World War One was 16 million.
The number of deaths as a result of the Spanish flu which followed in 1918 was somewhere between 30 and 80 million.

In the 14th century the Black Death is estimated to have killed 75 million people (including anywhere from 30% to 60% of Europe’s population – including Ireland).

 Which isn’t to say that the current Swine Flu shouldn’t be taken seriously, just that when it comes to risk our ability to be objective tends to go out the window.

The Black Death by Philip Ziegler is a book well worth reading for the historical and in particular the social and political implications of this desease.

Podcast on Leaving Cert definitions

Defintions

After taking so much time to put the last podcast together on neutrinos and then post about it, the hosting site Podomatic went down for maintanance for 24 hours. So I don’t know how that affected your feed, but if you got nothing then for once it wasn’t my fault. Unless the reason it went down was as a result of something I did, which would be impressive even for me.

Another possibility is that I after I uploaded the podcast so many people tried to gain access at the same time that the server just couldn’t handle the traffic 🙂

In which case a lot of people are in for a disappointment with this one. It consists of physics definitions which have appeared on leaving cert exam papers going back to 2002. When the new syllabus first appeared we were told that there was going to  be less emphasis on learning stuff  ‘off by heart’, particulary in relation to definitions. In practice this may well have been the case, the problem however is that because some definitions still appear, students have to cover all definitions to ensure they know the few which come up.

The syllabus is also unhelpful in that it’s not at all obvious what constitutes a defintion, but perhaps when the new syllabus comes out (in the year 20??) it may be more clear.

Apparently over 200 people have subscribed to this podcast, and that was after only two uploads, one of which was put together by two students.
One question: Why?

I think some people who were hoping to be entertained are going to be sorely disappointed with this one. No chance of it going viral then. It will be interesting to see if students find it useful. If you are a student don’t be afraid to let me know how I can improve.

I have put a link to both the podcast and the script on the Leaving Cert Revision page of thephysicsteacher.ie

Vodpod videos no longer available.

more about “Vodpod Firefox Extension for WordPress“, posted with vodpod

 

 

 

 

Dissection – great fun entirely

I have been experiencing a renaissance in my teaching life ever since I decided to embrace my ignorance on all issues biological (still can’t learn to love Chemistry unfortunately, but there may still be time).

We did heart dissections the other day.

I spent an evening searching for related videos on youtube. I am a firm advocate of the notion that unless you have been ‘prepped’ in terms of what to look for,you may well end up looking at an amorphous mess. In other words both the student and the teacher can be looking at the same object and see two completely different things. Discovery Learning obviously has its place, but as a teacher it’s all about knowing when to mix and match.

As usual there was a lot of sifting to be done before ending up with final list. As always, this is a labour of love.

Along the way I picked up the following nuggets:

  1. Each day your body makes 200 billion new blood cells.
  2. White blood cells live for two weeks, Red blood cells live four months.
  3. You have about 5 litres of blood in your body; when you donate blood you are giving up about half a litre.
  4. Your heart pumps about 70 times a minute, which equates to over 100,000 times a day!
  5. When exercising your heart-rate doubles to about 140 times a minute.
  6. Your heart is about the size of an apple.
  7. Blood takes about 35 seconds to make a round trip when relaxed, or 15 seconds when exercising.
  8. Heart Disease is Ireland’s number one cause of death.
  9. Irish women have almost twice the rate of death from heart disease as the EU average.
  10. The difference between a Heart Attack and a Stroke:
    Both are a result of blocked arteries: In a heart attack the blocked arteries are feeding the heart muscles, and those muscles are not getting the oxygen and nutrients they need to function.
    With a stroke, the blocked arteries are in the brain, and those brain cells are not getting what they need to function… depending on where in the brain it occurs, different functions are affected (e.g., speech, writing ability, and so on…)
    A third place where blocked arteries occur is in the lungs… then it is called a pulmonary embolism.

Ms Salter gave me a crash course on the dissection itself the day before, so I knew just about enough to set the troops on their way. They had an absolute ball, so why is this not a  mandatory activity? Why should non-specialist teachers like me get away with not doing such a memorable activity with my students?

I have since been informed that we can get hold of hearts which have all the tubes coming out of them, which should be much more educational.
I did tape the students doing the dissection itself, but accidentally taped over it. Sorry!
If doing it again I would  tell the students that their task is to teach another group about what they have learned. It tends to focus the mind!

I have put the youtube links on my website here.

Neutrinos, John Updike and Cosmic Gall

I’m suspect it may not have been part of his overall plan, but the death of John Updike coincided (can I say ‘nicely’?) with our class on Neutrinos.

There are some strange particles out there, but not many as strange as the neutrino.
Here’s what the syllabus has to say on neutrinos:

If momentum is not conserved, a third particle (neutrino) must be present.

And that’s it.
Here’s what Updike has to say.
This is why scientists need poetry.

Cosmic Gall

NEUTRINOS, they are very small.
They have no charge and have no mass
And do not interact at all.
The earth is just a silly ball
To them, through which they simply pass,
Like dustmaids down a drafty hall
Or photons through a sheet of glass.
They snub the most exquisite gas,
Ignore the most substantial wall,
Cold shoulder steel and sounding brass,
Insult the stallion in his stall,
And scorning barriers of class,
Infiltrate you and me! Like tall
and painless guillotines, they fall
Down through our heads into the grass.
At night, they enter at Nepal
and pierce the lover and his lass
From underneath the bed-you call
It wonderful; I call it crass.

Telephone Poles and Other Poems, John Updike, Knopf, 1960

What a wonderful counter to the claim that Science leads to a loss of wonder due to over-analysis (now replace ‘Science’ with ‘Science Education’ and that’s a different matter.)

Updike is referring to the fact that are about 50 trillion of these buggers passing through us every second! (rounded off to the nearest whole number, obviously).
I need to say more about these guys in a later post; their origins are just as amazing. Maybe I could use a podcast to try and get across the emotion that should be part and parcel of discussing neutrinos.

Anyway I say put that poem on the syllabus. And for the exam itself one word would suffice: “Discuss”.

 

Demonstrating how a tele works

Step One: Break the tele

Of course you could just shoot it

Then we looked at the working of the Cathode Ray Tube in a little more detail:
The cool thing about is that it enables us to look at the wave nature of the electron. Given that this (Quantum Theory) is one of the most popular areas of Science, you’d think that it would be on the actual syllabus.

“History repeats itself because no one was listening the first time.”

“That men do not learn very much from the lessons of history is the most important of all the lessons of history.”
Aldous Huxley

“If men could learn from history, what lessons it might teach us! But passion and party blind our eyes, and the light which experience gives us is a lantern on the stern which shines only on the waves behind.”
Samuel Taylor Coleridge

“What experience and history teach is this – that people and governments never have learned anything from history, or acted on principles deduced from it.”
G. W. F. Hegel

“Those who cannot learn from history are doomed to repeat it.”
George Santayana

“History repeats itself because no one was listening the first time.”
Anonymous

Taken from ageofthesage.org

The history of Easter Island is fascinating because it shows a civilisation slowly destroying its future in order to glorify the present. The people cut down their trees (which we now know were essential for their very survival) in order to carry stone for their famour statues, and must have continued to do this down to the last tree.
It would have make a nice moral story if the people had died off completely because they destroyed their key resource, but History is rarely this simple.
Nevertheless the moral still holds.

Watch The Mystery of Easter Island on youtube

The disappearance of the island’s trees seems to coincide with a decline of its civilization around the 17th and 18th century. Midden contents show a sudden drop in quantities of fish and bird bones as the islanders lost the means to construct fishing vessels and the birds lost their nesting sites. Soil erosion due to lack of trees is apparent in some places. Sediment samples document that up to half of the native plants had become extinct and that the vegetation of the island was drastically altered. Chickens and rats became leading items of diet and there are contested hints that cannibalism occurred, based on human remains associated with cooking sites, especially in caves.
From wikipedia