Before you start
Think it through first
Most popular
Construction Lab Compass and straightedge, exactly — an engine checks your construction and scores your move economy. 
Transformation Lab Slide, flip, turn, and scale shapes on a coordinate grid — name the move, predict where a vertex lands. 
Geoboard Stretch a rubber band around the pegs to enclose an exact area — and watch Pick’s Theorem balance. 
Geometry Duel A head-to-head kit round for 2–4 players — one device or an online room by code. Highest first-try score wins. All activities
Build & reason
Construction Lab Compass and straightedge — build a bisector, midpoint, or equilateral triangle; the engine checks it exactly. Property-Chain Reasoning Build a proof yourself — pick the deduction that follows next until you reach the conclusion. Fill the Point Which shapes tile? Place polygon corners into a vertex and fill toward exactly 360° — no gap, no overlap. Geometry Studio Make an angle to a target with a live protractor, build a polygon to an angle-sum, set complementary pairs. Transformation Lab Slide, flip, turn, scale on a grid — name the transformation and find a line of symmetry. Roll the Block Tip a tall block across a grid until it stands upright on the goal — a rigid-motion rotation of a solid; picture how it tumbles standing ↔ lying. Calm, no-fail. Geoboard Enclose an exact area with a rubber band and watch Pick’s Theorem balance as you drag.
Practice & play
Practice the concepts
All 17 kits
Kit 1: Points, Lines, and Angles Kit 2: Classifying 2D Shapes Kit 3: Area and Perimeter Kit 4: 3D Shapes and Volume Kit 5: Symmetry and Transformations Kit 6: Coordinate Geometry Kit 7: Pythagorean Theorem Kit 8: Geometric Proofs and Reasoning Kit 9: Circles & Arc Measures Kit 10: Similarity & Scale Kit 11: Intro to Trigonometry Kit 12: Geometric Constructions Kit 13: Cross-Topic Connections Kit 14: Real-World Applications Kit 15: Misconceptions & Reasoning Kit 16: Advanced Synthesis Kit 17: Congruence and Triangles
For grown-ups — progress report →
More ways to play
Same idea, another world
😄 Brain break
Meet the cast — the characters who teach this
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Master Hypotenuse Right-triangle relations: a² + b² = c² -
Lady Inscribed-Angle Circle theorems (inscribed-angle, central-angle, tangent-chord, cyclic quadrilateral) -
Sir Transverse Parallel-line transversals + intercept theorem (proportional segments cut by parallel lines) -
Apprentice Sides Area formulas (triangle area from side lengths; rectangle / parallelogram / trapezoid area) -
Captain Construction Compass-and-straightedge constructions (bisector, perpendicular, equilateral triangle, regular hexagon, circle-given-three-points) -
Compass Wraith Locus problems + circle-as-set-of-equidistant-points -
Madame Polygon Regular-polygon facts (interior-angle sum, exterior-angle sum, regular-tessellation, symmetry of regular n-gons) -
Master Tangent Limit-and-touch problems (tangent to a circle from external point, tangent-chord angle, tangent-as-limit-of-secant) -
Axia & Theora Twin theorists — Axia carries axiomatic-first reasoning; Theora carries theorem-application; together they bridge geometric postulates to derived results -
Madame Motion Rigid motions and congruence — sliding, turning, or flipping a shape never changes its size or shape; two shapes are congruent if one can be carried exactly onto the other. -
Scout Scale Dilation and similarity — resizing a shape by a scale factor keeps every angle the same and multiplies every length equally; similar shapes are the same shape at a different size. -
Lady Lattice The coordinate plane — every point has an exact two-number address, so you can plot it, measure the distance between two points, and find the midpoint exactly between them.
Ensemble stories — the cast together