Author: Emily Tietjen

Equilateral Triangle Puzzle

At the start of the school year, I came across this tweet by @MathEqualsLove… This Week’s Puzzle: Equilateral Triangle. This puzzle is always a favorite! #mtbos #iteachmath #teach180 #puzzlingclassroom — Sarah Carter (@mathequalslove) August 26, 2019 I loved the Equilateral Puzzle, so I finally got around to sharing it with teachers during a […]

Dice Tic-Tac-Sum

You’ll need a pen, piece of paper, and nine number cubes. Draw a tic-tac-toe board, and arrange the number cubes so that there is one cube per spot.  Change the face of the cube so that for every possible three-in-a-row (like Tic-Tac-Toe) the dice all sum to the same quantity. Of course, all dice being […]


Set (stylized as SET) is a real-time card game designed by Marsha Falco in 1974 and published by Set Enterprises in 1991. The deck consists of 81 unique cards that vary in four features across three possibilities for each kind of feature: number of shapes (one, two, or three), shape (diamond, squiggle, oval), shading (solid, […]

Four by Four NIM

Similar to Traditional NIM, two players alternate turns picking up tiles.  The objective is still to be the player to pick up the last tile. What is different is the arrangement of the tiles at the beginning of the game.  Tiles are arranged into a 4×4 grid, like so…   For this game players are […]

Eight by Eight Puzzle

A one-person game/Un juego de una persona Materials/Materiales One game board/Un tablero del juego 8 stones/8 piedras DIRECTIONS/INSTRUCCIONES Place eight stones in this shape so that NO two stones are in the same row, column, or diagonal (even the small diagonals). Coloque ocho piedras en la forma para que NINGUNA de las dos piedras estén […]


The tangram (Chinese: 七巧板; pinyin: qīqiǎobǎn; literally: ‘seven boards of skill’) is a dissection puzzle consisting of seven flat shapes, called tans, which are put together to form shapes. The objective of the puzzle is to form a specific shape (given only an outline or silhouette) using all seven pieces, which can not overlap. It […]