In a red brick building on a small street in Paris’ historic Latin Quarter, a group of high school students are trying to solve a puzzle. They have to recreate a football from memory, by sticking geometric shapes onto a plain sphere. It takes some mental gymnastics – hexagons seem like the logical choice, but it’s impossible to cover the ball using only this shape. After some frustration, one of them figures it out – throw in some pentagons at strategic locations, and the sharp angles disappear. The group rejoices. A version of this scene plays out five days a week at the Maison Poincaré, Fran…