Day 7: 7 blank bubbles to go.
We spent a lot of time with triangles in 9th grade Geometry, including the unforgettable Pythagorean Theorem Project for which we had to create 50 word problems, do the drawings, and then write out the math IN INK with no mistakes. Our teacher was a terror, or rather, she was a stickler for accuracy that was even then decidedly old fashioned.
9th grade grumpiness aside, my favorite math that year (and forever), was Solid Geometry, whose mathematical purpose of measuring the volume of solid spaces has never come up in conversation. While I don't recall the mathematical properties, I love the shapes. This lovely Small Stellated Dodecahedron has been used in art, and its celebration of the triangle makes it very dear to me.