Game of Tri

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Game of Tri
On display at Haus der Mathematik
Type Hands-on, two-player game
Topics Strategy

Game of Tri is a strategy game on display at Haus der Mathematik.


On a wooden panel, six pegs (nails, screws...) are distributed on the vertices of a regular hexagon. A box of rubber bands of two colors is available. With the rubber bands, we can join any two of the pegs forming a segment.

Activities and user interaction

It is a game for two players (each one has one color of the rubber bands). Alternatively, each player puts one band joining two of the pegs (that are not already joined). The goal is to be the first to make a triangle with three of the pegs as vertices (intersections of rubber bands are irrelevant). The game immediately recalls Tic-tac-toe. However, this is much less known and most likely each visitor will spend some time trying to find a winning strategy. While on Tic-tac-toe there is a strategy to force a tie (so one can always avoid losing), that is not the case in the Game of Tri.

Mathematical background

The exhibit is based on the following article, that makes an analysis of the game and its pedagogical value with children:

  • Haggard, Gary; Schonberger, Ann Koch (1977): The Game of Tri, Arithmetic Teacher, 24, 4, 218-320.


The game can be played online at the website of Haus der Mathematik.