Tuesday 13 October 2015


Gaslight is a creepy George Cukor film from 1944 starring Charles Boyer and Ingrid Bergmann here's the trailer.  You can see the whole of an earlier less hystrionic 1940 British Thorold Dickinson production starring Anton Walbrook and Diana Wynyard. The word has been subsumed into the English language along with hoover, xerox, kleenex and thermos: much to the annoyance of the corporations who want to trade on their invention. Gaslighting is a process whereby one tries to convince another person that they are losing their memory, perception or wits; rarely now by causing the gaslight to dim in a rickety Victorian house. You might think this is a rare enough occurrence but I did come across a thread on Quora the other day which gives numerous examples and a romp through the language of personality disorders. It can be extremely wearing to be party to such a transaction - either as gaslighter or gaslightee - so compassion is a better response than anger. We live in a very negative world: Google reports 10,000x more gaslighting hits than its antidote.

I had a nice case of the opposite, which I will now call ungaslighting, at The Institute last week. Two hours a week I have timetabled for QM Quantitative Methods with our 1st Year scientists, but we might also call it RM remedial maths. It's what we must do to combat the math-deficit among our incoming students. The bulk of the course in the first term is practice-makes-perfect on key math issues and we have used KhanAcademy for this purpose in the past but recently have switched to www.mathtutor.ac.uk a handy pro bono publico project launched by Loughborough Polytechnic University in East England. Mathtutor provides a PDF tutorial, an explanatory video and some exercises for each topic. Last week it was logarithms, the finer details of which are a bit head-wrecking, so you may need to read my earlier pitch for logs. On the front page of the mathtutor PDF are the Rules of Logs:
  • log(ab) = log(a) + log(b)
  • log(a/b)=log(a) - log(b)
  • log(am) = m log(a)
With that, even if you don't know exactly what is a logarithm, you should be able to answer a question like: determine the value of N, giving the answer as a whole number or a fraction.
In my Friday class is a very shy, very young-looking feller who is quite good at maths based on the result of my prequiz.  I have him marked down as "no probby", but halfway through the session he had his hand up asking for help on the question above. His answer was 2592/64:
N = 25 * 34 / 43 = 32 x 81 /64 = 2592/64
but The Computer [must be right is wrong!] was holding out for 2025/64 so he thought that he was missing something important. He looks like the sort of chap who has been told that he was wrong rather a lot: wrong haircut, wrong shoes, no piercings, no girl-friend etc. so has had a lot more tentativeness than assertiveness training.  But I assured him that he was correct and the computer was wrong . . . or at least I agreed with him and not the lads in distant Loughborough.  But I also said it might help if we find out why Mathtutor thought 2025/64 was correct. Find out why is, after all, what science is all about. Knowing your 81x tables helps: 25 * 81 = 2025. So Mathtutor had given the wrong, wrong almost right answer to log(N) = 2log5 + 4log3 - 3log4.  This is not the first typo we've discovered in Mathtutor and typos are a far more valuable learning experience than motoring through pages of exercises. If I was Loughborough, I would pepper in a few deliberate errors to jolt punters out of glazed-eyed sleeping-walking through the exercises. And my young chap can go home saying that he beat the Internet, which can't harm his self-esteem.

No comments:

Post a Comment