Letters - November 2008

Alan Dronsfield, Chair, Royal Society of Chemistry Historical Group

In On-screen chemistry (InfoChem, September, 2008) Jonathan Hare debunks the notion that a person in the film Murder ahoy might be poisoned by curare, delivered from the spike of a 'lethal' mouse trap. There is a second murder in this Miss Marple inspired film. The victim inhales powdered tobacco in the form of snuff and instantly and unspectacularly drops down dead. A heart attack is diagnosed, but Miss Marple, using a kitchen chemistry set, concludes that the snuff had been replaced by the poison strychnine. While it would be possible to deliver a fatal dose of the alkaloid by this method, the rest of the science is decidedly suspect.

Strychnine poisoning is a dreadful death and is far from instantaneous. Symptoms include tetanus-like convulsions, lockjaw, and frothing at the mouth. The victim dies either from asphyxia, or sheer exhaustion from the repetitive fits. Not a nice way to go, and certainly not the silent demise depicted in the film.

Crystal clear chemistry

Simon Cotton, Uppingham School

I congratulate Adrian Guy on his Exhibition chemistry series, which is a joy to read. When demonstrating displacement reactions and the reactivity series to my students I use a variant on the copper-silver nitrate experiment described in his recent article (see Educ. Chem., 2008, 45(5), 139). Put 15-20 ml of 0.1 M lead nitrate and silver nitrate and 0.2 M copper sulfate solutions in three different 9 cm diameter petri dishes. Cut small squares from a 0.3 mm thick zinc foil and using tweezers sink one in each solution. Do not disturb the dishes. Crystals of lead, copper and silver grow out from the freshly cut edges.

Is chemistry really back?

John Dexter, Trinity School, Nottingham

Colin Osborne's Endpoint on triple science (Educ.Chem., 2008, 45(4), 128) is timely but the situation may be worse, or better, for different schools. Many schools now have a specialism demanding curricula time; many faith schools also make religious studies compulsory before we get to healthy eating, citizenship etc all on top of maths, English etc. So the third part of the 'triple' may have to be a lesson(s) after school. Add in the extra homework (science now three times as much as maths for example) and one wonders what evidence there is that the triple award will drive more youngsters into chemistry or the other sciences? What too of the students who achieve A* in both physics and biology, but A in chemistry - will that huge potential not be realised? What of the youngsters who opt for double award, and turn out to be good scientists and enjoy their chemistry - will they now not consider post-16 chemistry because they feel second class, not having done the triple award?

Curricula designers seem to have forgotten that we went from the three separate sciences to double award because of time constraints and content overlap - nitrogen cycles in biology and chemistry; atomic structure in chemistry and physics. A move we welcomed - but as time has revealed, subtly, we stopped being 'chemistry' teachers and became 'science' teachers. Curricula leaders got us teaching parts of physics or biology, our lab became a science room - and some chemistry content went to those staff less sure of their chemistry. So the good news?

We can bounce back as chemistry teachers - better resourced (much thanks to Royal Society of Chemistry (RSC) education initiatives and resources) with clearer ideas of delivering chemistry. We can rebrand our rooms as chemistry labs and maybe rescue our subject and raise its value. The emphasis on performance may not go away but maybe the opportunity should be grasped - my new year 10 triple award students think so. We are only just beginning this journey, we may not know the uncharted consequences ahead but chemistry might just be back.

Multiple-choice questions can tick the box

Ann Hubbard, Surrey

I read with interest Andrew Hunt's balanced article on the value of multiple-choice tests as a means of assessment for the new GCSE Science curriculum (see Educ. Chem., 2008, 45(4), 117). As a teacher I was always keen on multiple-choice questions. I found this form of assessment could test students' recall knowledge very well. I used multiple-choice questions as an easy method to test students' depth of understanding and they could be structured to differentiate well across a whole range of grades. 

My students always enjoyed doing multiple-choice tests because the challenge of thinking towards a correct answer is rewarding. The students found the tests an excellent indicator of gaps in their knowledge and understanding as well as a good revision aid, ie a test list of what they should be able to do. 

I agree that the current style of marking/assessment does not have questions that really test application, evaluation and synthesis but these could easily be written in and tested in other styles of exam paper. I was sorry to see such questions disappear because they could access a wide proportion of the specification. I find today's papers predictable and relatively easy to get a good grade while leaving out several 'chunks' of the course. 

Good question writers are essential and this is a skill that is probably being lost along with copies of the old multiple-choice questions.