← Back to BAPHL 24 homepage

Turtle Geometry (Solution)

Turtle Geometry consists of a program written in the Logo programming language. However, unlike using a standard Cartesian plane, this program utilizes the surface of a sewer grate on the Watertown-Cambridge Greenway, viewed from above, as its drawing surface:

Sewer grate viewed from above

In order to execute the program correctly, teams first had to determine where to start. In Logo, the HOME command returns the turtle to the origin. In this case, the turtle’s HOME is next to WATER, indicating that it should start next to the word “WATERWAY” on the edge of the grate, “pointing towards a road or path” meaning that it should face the word “WAY”, i.e. counterclockwise:

Sewer grate viewed from above

After fully executing the program, the turtle would have traced out the following path (thin lines indicating where the “pen” was up, while thicker lines indicate where the “pen” was down):

Sewer grate viewed from above with turtle path drawn on it

Reading out the drawn letters gives the puzzle’s answer, METER