KML MathGeometry PuzzlesRuler and Compass Challenges
English

A line. A circle. A discovery.

Ruler and Compass Challenges

From a line through two points to a circle through nine. Explore with a ruler and compass, and discover the relationships behind each figure.

See how it works

No account · Local saves · Offline core drawing on Android

Nine-point circle puzzle showing a triangle, midpoints and construction lines
Actual Android test build · E06 nine-point circle

Availability

App StoreComing soon
Google PlayComing soon

Verified App Store and Google Play download links will appear after public release. No direct APK download is offered here.

KML Math

Four ways to explore geometry

59

Learn by doing

47 main lessons and 12 electives take you from points, lines and circles to perpendicularity, similarity and circle relationships.

6

Polygon challenges

Explore regular triangles, squares, pentagons, hexagons, octagons and 15-sided polygons, each with a new idea.

3

Daily challenges

A regular, challenging and brain-teasing puzzle, selected for your progress. Your daily set stays fixed.

∞

An open whiteboard

Pan, zoom, undo and redo with a full construction toolkit. Save work and export JSON, SVG or PNG.

Understand it. Then construct it.

  1. 01

    Find the idea

    Connect the given conditions with the goal.

  2. 02

    Follow a step

    Select a step to see the new points, lines and circles.

  3. 03

    Try it yourself

    Drag between points or tap them in order. Snapping helps you construct accurately.

This website is available in English, Simplified Chinese and Traditional Chinese. The App interface has three-language adaptations; complete puzzles, hints and extended lessons remain primarily in Simplified Chinese.

Before you begin

How much geometry do I need?

Start with basic points, lines and circles. G5–G9 labels describe the source of the knowledge, not an age restriction. Adults can explore too.

Why no regular heptagon?

These puzzles use exact constructions with an unmarked ruler and compass. Regular 7-, 11- and 13-sided polygons cannot be constructed exactly with those tools.

Can I continue on another device?

There is no cloud save. Export a whiteboard as JSON and import it on another device. This does not transfer all learning records.

Will daily puzzles repeat?

A generated daily set stays fixed. The bank has 45 distinct templates; progress and spaced review affect selection, so year-round uniqueness is not promised.