Letters - May 2009

RSC chief executive takes up GCSE gauntlet

Richard Pike, The Royal Society of Chemistry 

As a scientific charity, the Royal Society of Chemistry (RSC) must promote the chemical sciences and its education in a way that benefits the wider community, even if that means some groups may feel vulnerable in the light of what is being said, while others see their cause being strengthened (see Educ. Chem., 2009, 46 (2), 41).  

In the case of The five-decade challenge competition, our objective was to see how current 16-year olds could handle a range of single-step and multi-step chemistry-related questions, which demanded problem-solving skills, critical thinking and mathematical manipulation. It is no accident that such skills are what the most highly competitive UK companies and university departments in science are looking for in their employees and students respectively. The purely qualitative overview has its place, but nothing captures the mind more for understanding of cause and effect, and decision-making, than determining the quantitative implications.  

In our analysis of the competition we found that some participants were extraordinarily skilled in handling these types of problems. Significantly, however, we found the prevalence of multi-step questions in older papers, even where the science was topical and familiar, meant that many teenagers unused to this complexity had difficulty in achieving high scores.  

Our criticism lies not with chemistry teachers or pupils, but with an examination system that has marginalised the mathematical element of chemistry. Being able to appreciate the scale of things is desirable for 'good citizenship', and essential for progressing in chemistry post-16. While some observers have questioned the methodology of the competition, most teachers agree that there is an urgent need to embed mathematics more effectively into the GCSE science curriculum and assess it more rigorously.  

There is also other evidence that makes us realise that current GCSEs should come under greater scrutiny. In one of last summer's GCSE chemistry papers, a 'good' pass (grade C) could be obtained with a score of 18 per cent, suggesting there must be better quality assurance practices linking the curriculum, teaching, learning and assessment of these qualifications. Other reports show that league tables are driving schools to focus on middle-ability pupils to get a crucial grade C (rather than a D), at the expense of stimulating the brighter pupils who are expected to get an A*, A or B anyway. 

An increasing number of schools, albeit independent schools, are abandoning the current science GCSEs in favour of the more demanding international GCSEs. This will inadvertently create a two-tier science education system, which will inevitably disadvantage potentially high-ability pupils in the state sector. The time has come, we believe, to revisit what students should know, and be able to do, and how this should be assessed in the world we now find ourselves in.  

I believe that we have started a much needed debate on the mathematics content of GCSE science and assessment at this level, the outcomes of which should provide better science education for all.  

Declining standards

P. A. Barker, Blairgowrie 

In response to Peter Borrows' recent letter (Educ. Chem., 2009, 46 (2), 41), I was a chief examiner in GCE O-level chemistry for 20 years and, from time to time, we were asked by the subject officer for chemistry of the then London University Schools Examination Board to review the syllabus. On every occasion, we were told to reduce the content and especially, mathematical aspects, eg the mole, because difficult topics put students off the subject. I could list many other examples and I therefore agree with the Royal Society of Chemistry (RSC) that there is a lot of evidence to suggest that examination standards have declined.  

With regard to things like the colour of copper(II) sulfate, there is a certain body of knowledge that you acquire as you study a subject over some years. This is not the same as rote learning but you need to have this knowledge at your finger tips. While you can look up anything and everything in a book, this is not always convenient or appropriate. I recall the story of an undergraduate who was working in the lab but did not appreciate that ethoxyethane (diethyl ether) was explosively flammable. It might be a bit late to look this up in a book. 

Carbon monoxide sensors

Adrian Guy, Blundell's School

Teachers might want to add to my recent Exhibition chemistry demonstration on making and burning carbon monoxide (CO) (see Educ. Chem., 2009, 46 (2), 43) by showing their students the chemistry behind CO sensors used in the home. Simple CO sensors work on the principle that an ammonical solution of silver nitrate is reduced to silver metal (black) in the presence of a reducing gas such as carbon monoxide. Interestingly, the same reaction is used in the test for aldehydes in chemistry; the aldehyde functional group reduces ammonical silver nitrate to silver, producing the classic 'silver mirror' on the test tube wall. 

To make a simple carbon monoxide sensor soak a piece of filter paper in an ammonical solution of silver nitrate. 

Kit: 

• 0.1M silver nitrate solution; 
• 0.1M ammonia solution; 
• test tube;  
• watch glass; 
• filter paper. 

Method 

Add 10 drops of silver nitrate solution to a test tube. Add ammonia solution dropwise until the dark precipitate formed just re-dissolves. Pour the resultant solution onto a watch glass and soak strips of filter paper in the solution. Use the damp strips to test for the presence of CO.  

Eye protection - simply good practice

Hal Sosabowski, University of Brighton

In response to Lorelly Wilson's letter concerning my criticism of the lack of specified eye protection in Wholly irresponsible experiments!, when describing experiments with caustic reagents (see Educ. Chem., 2009, 46 (2), 41) I would like to make a few comments. First as someone who regularly does live, high hazard chemistry demonstrations I, and my team, always manage risk rather than avoid it. However, there is a difference between what I do and what I (or other professional chemists) tell young students to do when we are not there to oversee their activities.  

According to Wilson: 'The idea of risk from chemicals seems to apply only when it's a chemistry experiment'. This is not true. Builders, plumbers, painters, carpenters, vermin control, gardeners, surgeons all wear safety equipment when handling chemicals, and many household/DIY chemicals specify the use of eye protection. Wilson implies that cooking chips in a domestic science lesson would probably not warrant eye protection but if this same activity was done as a chemistry experiment, then it would. And I for one would make sure my students wore eye protection if they were doing such an experiment. 

Eye protection is part of the practical chemists' uniform. When chemists do an experiment they wear lab coats and safety glasses at all times so it becomes second nature. At the University of Brighton, our students are not permitted to enter laboratories without lab coats and safety glasses regardless of what they will be doing. This is for exactly the same reason that when entering a building site, all visitors must wear hard hats regardless of whether overhead work is taking place, because a building site is a place where things might fall out of the sky, and not because they probably will.  

Wilson is concerned that 'we are constantly upping the precautions to be taken over the use of what are very mild chemicals'. I would argue that these are mild chemicals when they are in a bottle in front of you. If they were to get on to your eye, they would not be so mild. There is a difference between sprinkling vinegar on your chips and having it propelled into your eye. But the point is that there is little cost/effort in putting on a pair of safety glasses when doing an experiment, but potential high cost in terms of health if you don't.  

If I as a writer describe an experiment that youngsters will then do, I would specify good practice, common sense and above all else execute my duty of care so that they are not hurt. It's not a great imposition to reach for a pair of safety glasses or even buy a pair from Homebase.   

I was recently musing over the number of times I had actually seen a potentially injurious eye-splash. The same day I had some visitors in the lab, one of whom had to be continually reminded to keep his safety glasses on. As we were clearing up I noticed that yet again his glasses were perched on his head, and asked him to replace them. Seconds later, a technician was washing out peroxide foam from a vessel and used too high water pressure, and peroxide-containing foam was shot on to the safety glasses of the person, who up until seconds before hadn't been wearing any. The silence was thunderous.