Remember the first time you saw a Möbius strip (the ring-shaped surface with only one side) and it felt like your world had been turned upside down? The hexaflexagon tends to have a similar effect. Only more so.
In this, her latest video, fast-thinking, faster-talking YouTube-maths-wizard Vi Hart presents us with the topologically fascinating hexaflexagon. First discovered in the 1930s by a daydreaming student named Arthur H. Stone, flexagons have attracted the curiosity of great scientists for decades, including Stone's friend and colleague Richard Feynman. Here, the ever-capable Hart introduces the folding, pinching, rotating, multifaceted geometric oddity with her signature brand of rapid-fire wit and exposition. She even shows you how to make your own.