As if she wasn't busy enough bringing up our daughter, and growing the new addition to the family, my wife is a part-time private tutor to several A-Level Biology students (A-Level, for those not from the UK, being the final hurdle students have to clear before University). These students must all have passed their GCSEs before being accepted on to A-Level courses, with exams including core subjects like English and Maths. But you'd never know it from the answers they give as my wife goes over practice exam questions with them.
Take percentages. One question involved converting a percentage to a frequency: if 5% of the population have the recessive form of gene X, how many is that out of 100? Blank stare.
Then there was a question about interpreting Echocardiogram (ECG) traces. You’ll have seen one these in the movies if ever there was a hospital death scene. As the patient breathes his last, the camera invariably pans to an ECG monitor at his bedside. The sound-track turns somber, the sun is blotted out by a cloud, and on the monitor the peaks and troughs of heart activity subside to the infamous flat line.
On an ECG, the trace shows activity up the vertical axis and time along the horizontal, so to calculate the heart rate (as the question required) you begin by measuring the distance between peaks on the chart to get the duration of each beat. The student could do that - counting blocks was within her skill set. But the next step was to convert that to a rate in beats per minute.
"It's not fair that they ask Maths questions in a Biology paper!", complained the student. My wife was taken aback for a moment – the girl apparently wasn’t joking.
"So what do you do now?", my wife prompted once she’d recovered.
"I don't know", began the student; then with sudden inspiration: "It's got something to do with 60 hasn't it?".
"Well, yes, it has,", my wife said encouragingly. "You know how long each beat lasts. Now you need to work out how many of those beats will fit in a minute. So what do you do?"
"Ah, I've got it now". The student's face lights up. My wife smiles hopefully. "You divide the time by 60!"