GamesThatTeach: “Let’s Play: Ancient Greek Geometry”

Excellent game for practicing circle/line/compass/ruler construction (as loved by junior-school maths exam writers): The regular polygons have been kidnapped by ninjas. Are you a bad enough dude/tte to construct the regular polygons with nothing but a virtual compass and straightedge?

“It’s a Compass and Straightedge tool/puzzle game written in JavaScript. I’ve always thought Geometric Construction felt like a puzzle, so to me this pairing was quite natural. Compass and Straight edge is a technique for constructing shapes out of circles, straight lines, and their intersection points. You can read the wikipedia here – but watch out, some of the gifs are spoilers for the game.” –

The exciting thing here is that it shows how to create “perfect” polygons – not estimated, not relying on a pre-made protractor / angle measurer, but 100% accurate, using rules of geometrical construction. For instance, here’s how to draw a perfect pentagon, without any tools beyond the compass/pencil/straight edge: