Category Archives: Science

A banker GCSE science question – the environment; what students need to know.

There is much media talk about environmental issues like climate change, renewables, air quality and pollution. Penalties for diesel cars to discourage nitrogen dioxide and particulate emissions are being introduced, and, astonishingly, the Tesla electric car company’s market value at £40 billion has now overtaken Ford’s despite only achieving a fraction of Ford’s sales. What can we say about the inclusion of these topics in Science GCSE? Well, firstly, there are lots of examples, and “environment” is one of the few certain, banker questions in the whole of the GCSE syllabus. Secondly, examiners are looking for proof that students understand some of the technical language involved. Let’s take a look in more detail.

Questions about the environment in general have become so popular in Chemistry, Biology and Physics papers, in both core and triple science alike,  that I sometimes think you just have to mention “carbon dioxide” and you are half way to a pass ! Even if  you are a climate change skeptic, suspend that view until after the GCSE’s! Certainly the payback on a relatively small amount of revision on a not-too-difficult subject is high since one or more questions will almost certainly feature – which cannot be said about all science topics. After last year’s “drunken rat” controversy, students tweeted that they had learned their CGP Biology guide religiously, yet so little of the syllabus cropped up.

A common fault amongst pupils is to confuse climate change and pollution, so that’s a good place to start.   Students should understand the following three key points:

1. All three of the sciences begin this topic with fossil fuels, which are mainly oil and derivatives like petrol, also coal and gas.

2. There are two separate consequences of fuel combustion.  On the one hand, the generation of the greenhouse gas carbon dioxide as a natural but increasing product of combustion. Then on the other hand emissions of bi products such as sulphur dioxide and soot  which cause pollution and smog.

3. And to counter these problems is the emergence of renewable energy sources such as solar power which reduce dependence on fossil fuel.

 

 

Candidates should ensure they understand both the advantages of fossil fuels and derivatives (fairly cheap, easily available, engines designed for them) and disadvantages (may run out, greenhouse gas generation, pollution, scars on the landscape). Similar pro and con assessments should be learned for individual, different renewables.
The basic mechanics of global warming should be understood. Rays from the sun entering the earth’s atmosphere bounce off the surface, and we need this to happen to a certain extent to prevent overheating; but increased CO2 concentrations don’t allow enough infrared radiation to escape, leading to a small but significant warming of the earth. (This is the way greenhouse glass works).

Some effects of global warming should be learned such as polar ice-caps melting; sea levels rising and coral reefs deteriorating as ocean temperatures rise; and species migration patterns changing.

 

Students should be able to interpret graphs such as global temperatures rising on the y-axis – but note the typically narrowed scale – with time on the x-axis, especially since the industrial revolution. These show global average temperatures rising around 1 degree C to 14.6 degrees, which alongside CO2 atmospheric concentrations rising from 0.028 to 0.038 % seem to provide a link.

Now let us summarise what revision is needed in each of the three sciences in addition to the above, and the type of question likely to be asked. (More detail is available in my coaching card lesson plans). Each science begins with the basic assertions above, then develops different angles.

Chemistry

Pupils should understand how fractional distillation of crude oil works, including generating products such as petrol and diesel fuels as described in this BBC video about Grangemouth refinery where I visited many times in my work.

 

Students should learn the basic word equations associated with combustion of fuels which are generally alkane hydrocarbons .

Hydrocarbon +  oxygen –> carbon dioxide +  water + energy released

and one example, for natural gas combustion.

CH4     +            2O2             →         CO2          +        2H2O

And also the word equation for acid rain, which damages buildings and statues, especially limestone :

Sulphur Dioxide + Water -> Sulphuric Acid

Students should also know the formulae of Nitrogen Dioxides (NO and NO2) and also understand how incomplete combustion produces sooty carbon particles (turning bunsen burners yellow) and in extreme circumstances the poisonous carbon monoxide (CO). Methods of reducing emissions are important such as scrubbers at power stations and catalytic converters on cars.

(In a sense I am pleased to see nitrogen and sulphur oxides (called colloquially “NOX and SOX”) being given priority once more. As a performance analyst in BP in the 1990’s I collated the emissions data from BP Chemicals’ factories including NOX and SOX. When CO2 was suddenly elevated to a much higher importance, I always worried that focus on these polluters might be lost).

The alternative fuels of particular interest in Chemistry are ethanol, bio-fuels like bio-diesel, and hydrogen along of course with their pros and cons.

The cracking of alkanes to alkenes and subsequent polymerisation also features in this context both for the fossil fuel origin and the non biodegradable nature of plastics.

Another branch of pollution features in metals extraction and mining, with heavy metal dis-colouration of rivers a possible disadvantage as seen in this article about the Colorado river.

Exam Questions have ranged from simple (what type of reaction is burning fuel in oxygen?);  to numeric (compare the parts per million figures for particulates, carbon dioxide, nitrogen dioxide for several types of fuel); to everyday experience (why do supermarkets charge for plastic bags?);  to involved (describe how a fractional distillation column works).

Physics

For Physics pupils need to know more detail about individual energy sources both conventional and renewable. The energy transfer steps for several of these should be understood. So for power stations running on fossil fuels, the transfer is from chemical (in the fuel), to thermal (burning it), to kinetic (turbines and generators); to electrical (the grid).

Nuclear power involves a plentiful supply of uranium and plutonium but they are finite resources so counted as non-renewable. And of course though they have the advantage of being green in a sense – no carbon dioxide emissions – the disadvantages include waste disposal and impact of major break downs (albeit rare) like Chernobyl.

The major renewable sources to learn are: solar panels and solar cells; wind turbines and wind farms; geothermal hot rocks; hydroelectric power; and tidal barriers. For each of these students should learn the energy transfer process, and advantages and disadvantages, perhaps two of each. For instance, for wind energy the transfer is from from kinetic wind energy to kinetic blade energy to electrical. The advantages include it’s renewable, and has zero carbon dioxide emissions and pollution; but it is not always available (when calm), the turbines can scar the landscape, and though costs are reducing they are expensive to build and maintain.

Typical questions have included: is global warming of 5 degrees C over the next 100 years a fact, a guess or a prediction?; why are copper pipes under a solar panel painted black?; calculate the cost of waste energy from a food processor and how it is manifested;  why do chemical salts used to store solar energy need a high specific heat capacity?; explain the difference in actual versus maximum electrical output percentages for a variety of energy sources; give 2 advantages and disadvantages of running gas fired versus nuclear power stations; why are transformers used between power stations and the national grid?

Finally, although electric cars are not specifically on-syllabus, that won’t stop AQA or Edxcel throwing in a wildcard question like “compare the advantages and disadvantages of electric cars versus conventional petrol or diesel engine cars”.  Answers should include reference to easy availability of petrol (difficult for electric chargers); petrol is from fossil fuel and so contributes to global warning (electric cars do not – though the charger itself has to be charged); petrol and especially diesel cause particulate, sulphur and nitrogen dioxide pollution whereas electric cars do not; and conventional cars currently have a higher mileage range than electric.(Note that a £300m electric taxi factory is opening in Coventry – truth is stranger than fiction as 3 years ago an A Level Business Studies question case study was built around just such a possibility, Even Business Studies is not immune from our topic ! )

Biology

Photosynthesis and the carbon cycle are highly relevant in this context.  This is a must for Biology exams, not just for the environment  question. The word equation for photosynthesis must be learned:

Carbon dioxide + water (with sunlight) –> glucose + oxygen
6CO2                  + 6H2O    light –>            C6 H12 O6  +      6O2

(The reverse equation for respiration of course also is important)

The carbon cycle includes the absorption of carbon dioxide through photosynthesis in leaves, and the production of carbon dioxide through respiration and also decay of dead animals, which eat vegetation.  This has been in balance until recently when from the industrial revolution onwards fossil fuel combustion is producing more carbon dioxide – only by a fraction but enough to mean an increase in the concentration of carbon dioxide in the atmosphere, which in turn links through to the so-called greenhouse effect and global warming.

In Biology, further emphases include the generation of another greenhouse gas methane through more intensive farming, and the reduction in CO2 adsorption through Amazon rain forest depletion, in tandem with the production of CO2 from burning those forests.

Fossil fuel pollution includes damage to leaves from acid rain because their waxy layer for mineral absorption is damaged, while health is affected by carbon monoxide because in red blood cells it binds more strongly to haemoglobin than oxygen.

Typical questions include; describe the main points of the carbon cycle and the role of photosynthesis; what can we do to slow global warming?; interpret a bar chart of billions of tonnes of carbon dioxide produced at each stage of the carbon cycle.

Summary

Environment as a subject is as near to a banker question as you can get, and one of the few where parents can easily help children, especially as GCSE age is just young enough for pupils to still accept parental advice! Further, you will hear almost daily on the news stories about this topic,  whose science may well feature in GCSE and so a round table discussion could follow at dinner. The key points are to start with are fossil fuels, but distinguish between carbon dioxide emissions – said to cause global warming;  and sulphur and nitrogen oxides, bi product polluters causing building damage and health issues. Then candidates should be able to explain the science and list some solutions for these problems. The examiners want balanced arguments, so be prepared to list both the pros and cons for conventional and renewable energy sources.

Biology GCSE drunken rats question

Three of my tutorial contacts talked to me today independently about the GCSE Biology exam that is going viral. I Googled “#aqa biology” and sure enough a torrent of links and Tweets popped up.

It seems that AQA included  questions in Biology GCSE biology about drunken rats, why boys drink beer and girls drink wine, including under aged drinking references, and a Business Studies question about what is an independent company.

Almost simultaneously a number of Scottish students complained that their Maths exam did not reflect the syllabus, and crucially “a common complaint was that the exam bore little or no resemblance to past papers and exemplar papers”.

What is going on? Let’s examine the issues, which raise important questions in general about the direction of exams. AQA are a terrific exam board, but have they got this one wrong?

First, this is not the same as last year’s most-tweeted GCSE Maths problem about “sweets in a bag: show that n²-n-90=0.” .  That was difficult, but on-syllabus, albeit requiring two rarely connected parts of the syllabus, probability and algebra. Not the same either as the “Scottish crocodile” question which was valid but ambiguously worded.

This year’s problems perhaps reflect a disturbing trend among exam boards. To appear to be “relevant”, “on-message”, “out of the box”, “contextual with society”, to focus on the “ethics of science” and “how science is applied” – rather than test simple scientific fact.  Also, a surely mistaken desire to be “cool with the kids”.  There is a whiff of Millenium Dome here – let’s make science exams more interesting and the kids will abandon their computer games and flock to science!

While some of these aspirations may be desirable their inclusion in vital exams is clumsy, unannounced and too dominant.  If such questions are included, it reduces room in the Hour test for basic questions about biology fundamentals. The implication is that examiners see science more as a matter of opinion, not fact.

Examiners, perhaps inadvertenly give the impression that they do not appreciate that teachers and children work very hard to learn the syllabus, practice on past papers, and despair when they open the exam paper and see a whole series of questions bearing little overt relation to the syllabus. They take the syllabus very seriously – more so than the examiners perhaps. It is like training all year to climb Ben Nevis, you reach the top exhausted, remove a prearranged stone from a cairn to claim your reward, only to find a message saying “Ha Ha, fooled you, you’ve climbed the wrong mountain!”  A teacher estimated that “only 25% of the course content” was covered in the Biology exam.

To paraphrase Donald Rumsfeld, known unknowns we can cope with, it’s the unknown unknowns that are the problem.

The question about “what is an independent company” was no doubt aimed at the idea of fair, not biased testing, and perhaps “controlled” and “independent variables”, but surely a better question would be, “why is an independent company used”? (for drug testing)?

biology2Some challenging examination of science experimentation and data analysis is fine – I am a data scientist and welcome the inclusion of graphs to represent data, and questions about interpretation.  Healthy living and drug testing are indeed in the Unit 1 specification. But when questions are sexist, appear to condone breaking the law, or are from another subject altogether, things have gone too far surely.

How many boxes can you tick in one question? Sexism, under-age drinking, animal testing, drug-taking, newspaper accuracy! One is tempted to ask, what were the examiners on when they wrote the question?! But seriously, didn’t the management have a quick sense check, and quietly suggest, ”I think you should have another look at this one, it is inappropriate”. Important social issues, but in a Biology exam? Better on Nicky Campbell’s excellent “The Big Question” on Sunday morning TV?

This raises questions about quality control at AQA, which along with Pearson/Edexcel and OCR is truly a great and professional organisation. (An independent company in fact, non-profit making)  I had assumed the Q stood for quality (actually it is for “qualifications” and AQA should remember that’s why pupils take the exam). One hopes this is a temporary blip. Questions like these are actually reducing standards not improving them.  If the majority of syllabus topics are no longer included in the exam, what’s the incentive to learn them?

I am detecting another general trend across exams. In their desire to become more challenging (good!) examiners are including more and more words in their questions, but not following through to ensure that the English is correct and unambiguous (bad!). An experienced tutor told me recently that sometimes a pupil often “has to guess” what the examiner wants.

Another question in the Biology exam is about Malaria. OK so far, it is in the syllabus. But the question is shrouded in “extras” – for instance needing to know Maths GCSE standard form “power of 10” notation. A core of scientific experimentation is to change and test one independent variable at a time – but here the examiners themselves are simultaneously testing biology, and beyond-basic maths.

AQA have responded and are standing by their exam, saying they do not want it to be “predictable”. I have taught and trained many pupils and adults and what I have found is this: provided they are given clear instructions with no surprises they will pursue a difficult task to completion, otherwise many become confused and disheartened. The danger for AQA is that in their efforts to make science more “interesting” and “challenging” they will discourage interest, especially as these questions were in the basic science Unit 1 paper. They seem more appropriate for advanced students

The fact that AQA felt the need to explain the question on social media at all suggests it wasn’t very clear in the first place. The fact they defended it suggests we should expect more of the same, we should “expect the unexpected”.  This will mean more teaching time is dedicated to predicting and practicing for these flowery questions, and less time for the fundamentals of biology.  Examiners may be surprised, but optimising your grade really does matter.  Appliance of science is of course important, but not at the expense of simply knowing the fundamentals?

At the risk of sounding like a “grumpy old man”, and another thing: core Unit 1 science GCSE contains no questions about electrical circuits or electrical safety but generally contains questions in Biology, Chemistry and Physics about the evils of fossil fuels,  carbon dioxide and global warming. On-message indeed!

The other issue emerging is the annual use of Twitter and other social media by pupils to vent frustrations with exams. While I am not a great fan of “trial by social media” I think this method of scrutiny is here to stay and exam boards must expect more in the future.

In summary, my beef is this. Though “application of science” is directionally right, and AQA are a fine organisation, the quality control on questions needs to be stepped up.  We need less social posturing in science exams. The syllabus content may be reasonable, but the questions do not sufficiently or overtly reflect the syllabus.  And when they do, they are shrouded in unnecessary, periphery extras, obscuring the basic facts around the subject.

A GCSE Chemistry substance found on planet Mercury

mercuryNews today from the NASA Mercury probe that an unexpected substance has been found on Mercury, in fact making up the outer crust of planet Mercury. The substance is graphite, which will be familiar to GCSE Science and Chemistry students, not only because it is used in pencil lead due to its slippery nature and black colour, but also because its unusual structure is frequently the subject of GCSE questions.

graphiteGraphite is made of carbon atoms, arranged in layers in a giant covalent structure. While the bonds between adjacent carbon atoms are strong covalent bonds, the bonds between layers are weaker enabling slippage to occur. Further, the structure includes “free electrons” enabling graphite to conduct electricity. This is highly unusual for a covalent, non-ionic structure, as is its high melting point. Graphite is also used as part of nanotubes in tennis rackets.

 In some senses graphite is like diamond because it is also a giant covalent structure of carbon atoms, but in diamond there are no layers, just a continuously strong bonding arrnangement making diamond much harder. And of course you’d look a bit silly with a pencil for an ear-ring.

What other GCSE substances are there on planets in our solar system? Well, on many planets we can find an iron and nickel crust, and on Mars recent photogrpahs indicated the possible presence of both water and methane, with the water creating channels that are still changing in appearance.  This indicates that the water is still moving and not completly frozen, perhaps because of hydrated salts, which lower the melting point.

BowieThis, together with the presence of methane (carbon with four hydrogens – natural gas – and another GCSE bonding question) indicate that Life on Mars is possible. And so I need no excuse to include a video from the sadly missed David Bowie’s Life on Mars, one of the great rock records.

So it may not get you any more marks, but in a GCSE question it would surely look cool to your examiner that you knew that graphite had been found on Mercury and methane and water on Mars !

As a footnote, a wonderful website called PeriodicTable.com contains picture links to all the elements, including carbon of course – try it!

Colorado yellow river pollution in GCSE?

The VW nitrogen oxide and now CO2 saga shows that pollution is still a concern, and reminds me of the recent story of heavy metal pollution in Colorado turning a river literally yellow: could it feature in GCSE Chemistry?

coloradoTruth is stranger than fiction. The theme of the Simpson’s movie was that the USA Environmental Protection Agency (E.P.A.) turned into bad guys and erected a giant dome around Springfield in an attempt to contain the water pollution that Homer had started.

In August however the tables were turned when the real E.P.A, accidentally pumped polluted water into a Colorado river while clearing up a mine. The pollution spread and extended over the border to New Mexico and the river turned yellow, becoming contaminated by heavy metals including lead, iron, zinc, copper, mercury and arsenic. Read more in the BBC’s account and CNN broadcast

Could pollution and heavy metals feature in GCSE chemistry? Well, it is at the margins, but yes they could. Heavy metals are amongst the transition metals of groups 2 and 3 of the periodic table, of which students must know the layout. 

Pollution as a whole is often featured these days in GCSE chemistry as a supplementary question, sometimes around acid rain. For instance one specific sample question was to “list the advantages and disadvantages of mining metal ores” to which a good answer might include “they can cause difficulty in clearing up once closed down, as shown in a recent incident in America”. It is worth students talking to their Chemistry teacher about the incident.   

Water purity sometimes crops up as well in GCSE, with one of the purposes being to remove heavy metals.    

It remains to be seen whether the American Government will fine itself several billion dollars, as they did to BP after the Gulf of Mexico oil spill (I declare an interest as a BP shareholder and former employee !) The affected Narajavo Nation for instance is already threatening to sue. It reminds us in Europe of the sad decline in colour of the Blue Danube.

easyriderTo finish on a lighter note, while Yellow River certainly was not a Heavy Metal record (it was by UK Group Christie) it is worth mentioning the possible origin of the term Heavy Metal. In Chemistry it is because the metals mentioned have high relative atomic mass. In music it is probably from the phrase “heavy metal thunder” in Steppenwolf’s “Born to be Wild” which featured in the biking film Easy Rider (above) , or from the title of Iron Butterfly’s 1968 album “Heavy”. Many songs claim to be the first truly heavy metal song, the most famous of which are the Kinks “You Really Got Me” and  the Beatles’ “Helter Skelter” at the end of which Ringo, after drumming so loudly, famously agonises “I’ve got blisters on my fingers”!

GCSE-taking teenagers (OK, of the boy variety) will probably associate  heavy metal most closely with AC/DC, and their soundtracks from the films Iron Man 2 (Robert Downey Junior) and Battleship ( Liam Neeson, Rhianna), or from the video games like Rock Band and Mad Max. Parents may be interested to know that AC/DC’s Back in Black is the second highest selling album ever behind Michael Jackson’s Thriller, and ahead of Pink Floyd’s Dark Side of the Moon, Whitney Houston’s Bodyguard, and Meatloaf’s Bat Out of Hell. Could there be such a diverse set of albums?

Headmaster suspended for letting pupil take exam early

A headmaster in Wolverhampton has been suspended, and then reinstated after an enquiry, for allowing a pupil to take a GCSE English exam a day early. The reason seemed a little lax, namely to allow the pupil to go on holiday with their parents.

One assumes the enquiry involved checking his phone records and those of his friends in the few hours after the exam!

It reminds me of another “exam made easier” story from June when the answer to one GCSE question was helpfully supplied in another question, in the same paper. An AQA Chemistry paper contained the following:

2a. Fill in the blank. Limestone is mostly calcium ————
5b Limestone is made mostly of calcium carbonate…

In terms of making exams easier, let’s finish on a more serious note, well slightly more serious; allowing computers in exams.

googlemathsThe head of the OCR exam board suggests that Google be allowed in exams. The responses have varied from “ridiculous” and “rubbish” to “it would test resourcefulness and initiative rather than just your memory”.

Another proponent of the use of computers in exams is Dr. Sugata Mitra who conducted the famous experiment to place a computer in a hole in the wall adjacent to an Indian slum and found 7- year old children very quickly picked up skills with no assistance. It is a topic that won’t go away. But that is for another blog!

Could you wear Pink Floyd in Physics exam?

Pink

I, like many aging rockers, proudly wear my Pink Floyd Dark Side of the Moon T shirt around the house.

So the question is, could a pupil wear this in a GCSE physics exam, and would it be of any use?

The answers are possibly, and yes.

Most pupils have to wear school uniform in GCSE exams, but it is possible some don’t (think re-takers or adult education).  But it is likely they would have to change or cover up, as “notes that would help” are precluded.  If however all those barriers were crossed, would it actually be of use? The answer is definitely yes. Useful both to you – and here’ s the catch – everyone else!

A very typical Physics GCSE question might be to predict and explain the path of white light entering a prism, and what would the positions of red and violet light be?

The T-shirt goes a long way to answering the question.

White light disperses as it enters a prism because different wavelengths of light refract by different amounts. Unlike a rectangular block, the boundaries of a prism are not parallel so the different colours of different wavelengths do not recombine.

But why is red at the top of the spectrum and violet at the bottom, and how do you remember which way round it is? Well, red has the longest wavelength of the visible part of the electromagnetic spectrum and is refracted i.e. bent the least, whereas violet has the shortest wavelength and is bent the most.

How could you remember this? For the exam you certainly need to learn the key parts of the whole of the electromagnetic spectrum from radio waves down to gamma waves; and within that, the order of the visible light colours – but how to do that? 

Well, you could wear the T shirt and be asked to leave the exam room. or use a technique close to the Mathemeteer’s heart – the mnemonic (always wondered how to spell that!)

Richard of York Gave Battle in Vain       Red Orange Yellow Green Blue Indigo Violet!

Pink Floyd’s chorus children famously sang “We don’t need no educashion”. Oh but you do!

Maths and the NPL Music Society

NPLConnections between Maths and Music are many and varied. Here is another, indirectly at least.  In Teddington the National Physical Laboratory and “Home of Measurement” plays host to the NPL Music Society, where small classical music lunchtime concerts are given in the Scientific Museum, Bushy House.  These concerts feature pianists, singers, small chamber groups and recently a harpsichordist who perform in a room overlooking Bushy Park, while surrounded by all manner of scientific measuring instruments. The next performance is Thursday October 22nd   2015, featuring Haydn and Granados.

Meanwhile at Waldegrave School in Twickenham, a representative from the NPL recently gave a talk to the 6th Form Physics Group on the subject of standardised time zones and time measurement.   Before the advent of the railways in the mid-19th century there were no standard time zones in the UK, and time differences between cities could vary by as much as 20 minutes, as explained in this article.

The NPL is home to the first Atomic Clock developed 60 years ago this year. The Caesium atomic clock is accurate to 1 second in 158 million years.

Maths GCSE includes questions on converting ratios with different units into “1 to n” ratios. It is an extreme example, but in this case the accuracy would be 1 to 158, 000,000 times the number of seconds in a year, which is 31,556, 926 (you didn’t know this? Nor did I!). Making  :  4,982,688,000,000,000 in all, or about 1 in 5 million billion. 

If you find that mind boggling consider this: the next generation of atomic clock will make the above look piffling, and will be 100 times more accurate, making an accuracy of 1 second in the age of the universe. I cannot get my head around that! It presumably would enable us to figure out if the Big Bang was late in coming, but that is another story, although Big Bang is actually covered in GCSE Science and Physics and also in Religious Studies.  More on that another time.

Meanwhile back where we started, here is a link to an extensive review of a NPL concert from a couple of years ago and a more recent advert for a December 2015 concert featuring Natasha Hardy.