Geometry is one of the few sort of maths that uses visual logic. After all, even if you didn't understand whatever problem was on hand, you could usually puzzle it out by simply looking at it.
Back in 1896, students were expected to learn using the same basic principle. These elegant gridded prints -- snapped from a vintage Swedish geometry text book -- each illustrate a different geometric principle of a An elementary treatise on analytical geometry, the 1860 paper of a French mathematician and astronomer named Jean-Baptiste Biot.
Thankfully, most of us are of an age when we can afford to hang them on our walls, rather than furtively pour over them for the half hour before a test. Hope you did well in school (or are independently wealthy) though: at $US995 per piece, these prints are exorbitantly expensive. [Dwell Studio]