Mnemonic devices – those little tricks and shortcuts we teach ourselves to help remember things – are almost always verbal. They can rhyme (I before E, except after C) or spell out hints (ROY G BIV). But where are the great physical mnemonics?
At least two memory triggers rely on the human body, instead of simply words. There's the Lefty L trick, in which you teach kids left from right by asking them to extend their pointer finger and thumb to see which one takes the shape of an L. There's also the more obscure Monthly Knuckle technique, in which you count the months on your knuckles and the valleys between your knuckles, skipping your thumb knuckle; every month that lands on a knuckle is 31 days.
A recent tweet offers a whole new frontier for potential physical mnemonics: dancing mathematics.
Several people have posted this image on Twitter, but we first spotted it thanks to Australian numberphile Simon Pampena.
The uncredited illustration shows off dance moves for 15 different mathematical equations. Rather than rely on a graphing calculator, the stick figures use their arms to represent each equation, from the disco-like y=x^3 to the walk-like-an-Egyptian y=sin(x).
This hand-drawn chart racked up more than 2,000 retweets over the weekend. But before you start your own algebraic boogie, take a second look at the dance line. Some of these doodle dancers have their equations mixed up. For example, y=sin(x) is backwards – you will want to flip the position of the left and right arms – and y=log(a^x) is upside-down. Also, we'll forgive y=1/x for making the most of a physically impossible move. The human body isn't really built for double-axis asymptotes.
Do you have a favorite physical mnemonic, or maybe a new mathematic dance move? Let us know in the comments.