None of the above

[gareth_rees]

As background for an article complaining about falling standards in education, The Times scanned and posted the 2006 Edexcel GCSE Science: Physics P1b exam paper. This is a multiple choice paper covering topics of waves, electromagnetic radiation, astronomy, cosmology, and seismology.

I don’t necessarily concur with the judgment of the article (

Comments

[autodidacticphd]

i love what you are saying here. exams, especially multiple choice, need to be written accurately in order to test the knowledge of the students... not just to test what a student may have been lead to believe through the course. this is especially a problem for students who have a strong auto-didactic streak and may know more about a subject than is covered by the course materials and lectures. i've found myself frustrated by poorly written exams on many occasions, even in math classes, where there are often multiple ways to approach a problem, but the particular course may not include all methods. there are also problems of notation that can lead to ambiguity if the students have not been exposed to all possible representations

[gareth_rees]

Yes, obviously the examiner wants "D" for 31. But this is typical of the carelessness toward science evident in the way these questions have been written. It's like the skin cancer question: presumably there the examiners want the answer "C" (ultraviolet) because that's the fact that's on the syllabus. The examiner doesn't know much about the subject being examined beyond what's listed in the syllabus, and doesn't care enough to find out. It's education, but it's not science.

[nickbarnes]

Yikes. This is horrible. To nitpick upon nitpick

[nickbarnes]

Enlarging on that point: as I understand it, one needs a degree in at least a related subject in order to teach GCSE subjects. So how come the exams are being set by people who would fail an introductory course in arse-finding (special credit for using only one hand)?

[gareth_rees]

I thought about microwaves but wasn't sure: repeated burning of tissue is another cause of skin cancer, and microwaves of sufficient power can heat skin, so I think it's medically plausible. But I couldn't find any evidence of it actually happening in real situations (just a lot of studies finding no evidence that mobile phones/Wi-Fi/microwave ovens cause cancer), whereas I could find cases for the other kinds of radiation. Here's a study showing that microwaves can accelerate the development cancer in cancer-prone strains of mice.

questions 6 and 7 are both entirely bogus.

Some of the commenters on the Times article wondered if this was part of a programme of indoctrination: teach children about iris scanning, then when they grow up they will be less likely to object to it.

Question 33 is problematic, because (as I understand it) the proportions of baryonic matter, non-baryonic (dark) matter, and dark energy are now highly constrained by models of the Big Bang. This 1995 paper sets out the theory; on Wikipedia, see Lambda-CDM

[nickbarnes]

questions 6 and 7
I guess my point here is that there are actual deployed systems which do identification based on irises, retinas, faces (of which eyebrows are an important part) and I dare say on scleral blood-vessel patterns. And these actual deployed systems are used in a variety of settings including airports but also including offices and military bases, and probably also including hospitals, schools, offices, homes, vehicles, and examination board arse-finding competitions.
So this is ignorant, as well as being indoctrination. And it also has absolutely fuck-all to do with physics. Really, nothing at all. It has a little tiny bit to do with biology, I guess, and maybe a bit to do with IT, and a lot to do with sociology, and politics, and history, and philosophy, and "citizenship". But not physics. So what the hell is it doing in a physics paper? I mean, where are the questions about reality TV, or gardening, or french poetry?

The Edexcel Physics Specification

[manjushra]

Is here:

http://www.rewardinglearning.org.uk/qualifications/results.aspx?g=2&t=4&s=75&v=0&d=r

which is 65 pages long. So far I have found that while a student is expected to be conversant with the Big Bang model, that model is not further defined in the spec. And there's no requirement to know anything about dark matter. SO the fault is with the astronomy question setter, rather than with Edexcel.

Re: The Edexcel Physics Specification

[gareth_rees]

It's not really the job of the syllabus to define the topics it lists; that's for the textbooks and the teacher. But yes, the question setter is at fault, not the syllabus creator.

I find it slightly sad how many of the syllabus requirements are in the form "recall..." and "describe..." rather than "explain..." and "calculate...". But it is GCSE, and it's supposed to be applicable to the full range of ability levels, not just to the ablest 25% like O-levels were twenty years ago.

Re: The Edexcel Physics Specification

[manjushra]

But it is GCSE, and it's supposed to be applicable to the full range of ability levels

Which is progress, I think.

The Times article quotes Dr. Sinclair, head of Joint Council for Qualifications:

Dr Sinclair added that the changes would help to stop children being “turned off” by science. “Part of the desire is that the student can come out of the exam with a feeling of success that they have actually tackled a significant proportion of the questions, and achieved the best grade expected,” he said. “The vast majority of candidates taking this exam are going to achieve grades D to G, and they deserve a positive experience of science. “They can only have that by being allowed to attempt questions which are at their level . . . It is making exams accessible to candidates.”

Re: The Edexcel Physics Specification

[manjushra]

_Someone_ has to define topics and approve the reliability of what is taught. Is that down to the teacher? The textbook writer? The headteacher who decides which textbooks to buy?
I am musing now, what checking mechanisms there are in education to ensure that teachers are teaching what is currently perceived as Truth, and where this Truth is defined.

I'd expect to find it in the National Curriculum (http://www.nc.uk.net), but on the vexed subject of astronomy, this is all it dictates:

The Earth and beyond
4) Students should be taught: The solar system and the wider universe
1. the relative positions and sizes of planets, stars and other bodies in the universe [for example, comets, meteors, galaxies, black holes]
2. that gravity acts as a force throughout the universe
3. how stars evolve over a long timescale
4. about some ideas used to explain the origin and evolution of the universe
5. about the search for evidence of life elsewhere in the universe.

[gjm11]

Ow ow ow ow. The stupid it burns. Etc.

Most of the questions have already been demolished. Let me add a couple more.

Q18: You keep using that word "measure". I do not think it means what you think it means.

Q37: these "classification charts" are truly bizarre. They look like Venn diagrams, but actually I take it they're some sort of dual to Venn diagrams. Does anyone in the real world actually draw things like this?

Q38: AIUI has no correct answer. I suppose the examiner is hoping for B, but if the world's seismologists were presented with a really detailed 3D model of the earth's structure as it currently is I don't think it would make much difference to their ability to predict earthquakes.

I love (where by "love" I mean "cringe at") the blurb before question 17.

[gareth_rees]

Q18. I don't see what's wrong with using a ruler to measure wavelength, where the waves can be made visible. For example, a vibrating string contains a standing wave; the wavelength is twice the distance between nodes, and this can be measured with a ruler.

(The answer to Q18 is feeble, though.)

[gjm11]

Using a ruler to measure the wavelength of sound is like using a voltmeter to measure light intensity: you can do it, provided you have some other apparatus (some more visible thing you can induce to vibrate along with the air; a photoelectric cell), and I'd say that what's doing the "measuring" is the whole apparatus.

The analogy isn't quite fair, since once you've made your waves visible by whatever means you can indeed quite literally measure the wavelength with a ruler. I still think the language in the question is very odd. Maybe a better analogy: "How can we measure the day-length of a planet around a distant star?" "Use a Foucault pendulum."