In the comments to the post about the cartoon with the cosine pun, many people recalled the mnemonics that they were taught to remember how sine, cosine, and tangent were defined. In the comments, Rob Grigjanis mentioned the mnemonic he learned for the color spectrum as “Richard Of York Gave Battle In Vain” and that reminded me of this story that I have written about earlier that happened when my older daughter was in third grade.
She came home from school one day and told me excitedly how the teacher had explained how white light was made up of different colors. The teacher had also told her that the great scientist who discovered this was Roy G. Biv! To say I was surprised is putting it mildly. I tried to gently correct her about who the scientist was without seeming to disparage her teacher, but my daughter was skeptical about what I was telling her. Who was she more likely to believe: her teacher, a fount of authoritative knowledge, or her dopey old father, often prone to making jokes? She was too young to appreciate the implausibility argument that it was highly improbable that the scientist who discovered the color spectrum just happened to have a name that matched the initial letters of the colors in the right order.
Growing up Sri Lanka, sophisticated mnemonics such as these were not a thing and I did not recall that we were taught any for the trigonometric ratios or indeed for anything else. I found those trig definitions pretty easy to remember. For things that were more complicated, we just made a crude mnemonic by making the sequence of first letters into a word. We learned the order of the colors by saying ‘vibgyor’ pronounced phonetically, so that it sounded vaguely Hungarian. Roy G. Biv never made an appearance. Another one was ‘bodmas’, for the order in which mathematical operations had to be done in an expression that combined many operations. It stood for ‘brackets, of, division, multiplication, addition, subtraction’.
The fact that I still remember them testifies to the power of such devices to remember things.