Noisy calculators
For part of my part-time degree course (1970-75) I did a module, I think called “mathematical method” which involved doing complex computation using one of those handle driven machines. It was fun practising and whirring the handle round at a rate of knots; however, at formal exam time I found myself in a huge hall with literally hundreds of fellow maths students, all whirring their handles so fast the the accumulated noise was deafening. I just went into hysterics and am still surprised that I ever passed.
Lesson learnt:
[ Perhaps a lesson to be learnt here is that technology's side-effects can be distracting? Richard Millwood, editor]