What novel ways have been used to present proofs or (more generally) mathematical ideas? I've encountered people answer olympiad problems with proofs written as limericks and sonnets before; there's also the Socratic dialogue, used by one student in a selection test and later to popularise the elementary measure-theoretic proof of Poncelet's porism: https://cp4space.wordpress.com/2014/04/19/poncelets-porism-the-socratic-dial... I've also heard of lecture in which the lecturer wrote down the truth table for logical conjunction on an overhead projector transparency like so: t ^ t = t t ^ f = f f ^ t = f f ^ f = f He then flipped the entire OHP sheet over, transforming every AND into an OR whilst transforming the `f's into `t's and vice-versa. Indeed, this is not the only spectacular use of an overhead projector. The late Christopher Bradley famously used an overhead projector to demonstrate projective transformations in a beautifully literal way: he tilted the projector, demonstrating the following concepts: -- Interchangeability of different types of conics; -- Interchangeability of parallel lines and convergent lines; -- Preservation of collinearity and concurrency; -- Conservation of cross-ratio. Any other examples of novel presentations of mathematical ideas? Sincerely, Adam P. Goucher