themes

geometric designs

simple designs, envelope doodles, bipartite graphs,
drawing labyrinths, modulo-phyllo, knot tiles

shapes with paper

origami butterflies, paper rhombic hexecontrahedron,paper rhombic triacontrahedron, edge colored icosahedron, origami cup, origami frog, knot tiles, window patterns, silver rectangle window patterns, spherical tetrahedron, origami envelope

shapes with numbers

polygonal numbers, mandelbrot set,
 finding polygonal numbers in multiplication tables, 

lucas number triangle, catalan number triangle, 

harmonic denominator triangle, euler's number triangle, 

something surprising in pascal's triangle,
tesseracts and factors

chess-related

knight's path puzzles, king's path puzzles, more knight's tour puzzles,

 knight moves, closing knight's tours, punctured tours

spirals

spiral drawings, sequences on number spirals, polygonal numbers on spirals

phyllotaxis, primes on a log spiral, hypocycloid scrambler and scrambler fractal

book reviews, other ramblings

mathematics of ancient Iraq, the best mathematics writing of 2011, mere calculation,
the math humor of Stephen Leacock,  

math as a tree, old math books, mathematics and friendship,
species and culture of mathematics,
jump math, halmos aphorisms

things from school

means and trig ratios, polygons and multiplication, 

polynomial division: the grid method,
multiplication table rainbows, grade one functions