Sherlock Holmes solves physics problems!

Magnifying glassConversations with my A level physics students over the past couple of weeks as we prepared for their January exams, seemed to develop around a recurring theme, i.e. talking about exam technique and how to tackle individual questions, and how that reminded me of how Sherlock Holmes solved crimes!

So, you’re probably wondering, what’s the connection between crime-fighting in Victorian London and A level physics?

The guiding principle behind Holmes’s impressively successful problem-solving technique might be crudely summarized as:
The simplest solution that fits the facts is the one most likely to be correct.

What I’m really getting at is the observation that many A level physics students have a tendency to overcomplicate things, especially when it comes to answering exam questions. This can frequently arise when a student thinks a particular exam question is harder than it really is – the common upshot being that they then get themselves into unnecessary complications, and subsequently fail to pick up all of the available marks.

Lots of physics students are often intimidated by those long, written answer questions. For example, take a fairly typical A2 question on electromagnetic induction, such as:
“Describe the action of a step-up transformer. Your answer should refer to the parts played by the primary and secondary coils and the core of the transformer. (Marks may be awarded for the quality of your written communication).”

Panicked by the prospect of filling half-a-page of empty space for a chunky ‘6 marks’, and not knowing how to begin, many students will typically fling all of their knowledge about electromagnetic induction into the first sentence, stuffing it with references to Faraday’s and Lenz’s laws. By the time they’ve finished (trying to describe the whole of electromagnetic theory in a dozen lines of unpunctuated text along the way), they’ve probably barely mentioned what the transformer actually does at all!

Students would do well to remember that exams are set to assess students at all levels – from those who will just scrape a grade E, right through to those who will comfortably achieve an A*. Sure, there will be bits on any exam that are there to stretch the most able, but if all the questions on the paper only sought to do that, it would be a pretty rubbish exam and useless at assessing students’ knowledge and ability (which is all any exam is created to do after all).

So, what is a good strategy for those sorts of questions? Well, I’m a fairly uncomplicated sort of person, so I like simplicity. When tackling big, wordy, descriptive-answer questions, there’s usually a mark for stating the obvious, so begin with that! Thereafter, the rest of your answer should just be broken down into simple, logical steps – straightforward statements about the system being considered, matched up with concise descriptions of the physics behind it.

Similarly, when trying to figure out how to tackle tricky-looking calculations, if you are stumped as to which equation to apply, a useful technique is just to try and think of the simplest (relevant) equations first and see if the data can fit any of those, before reaching for the more complicated equations from your formula sheet.

This advice might seem trite or oversimplistic, but experience has shown that it works! Exam technique is not some mysterious or difficult thing to acquire; the principles behind optimal exam performance are straightforward enough – what’s required is a thoughtful and self-reflective approach applied to plenty of examination practice. Consciously trying to look for the simplest way to solve a problem is just one more weapon in your armoury…
it worked for Sherlock Holmes!

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