📐 Math
Geometry
Angles, triangles, circles, area, volume and proofs, with pictures and stories that make the rules easy to remember.
Aligned to the Common Core High School Geometry (HSG) standards. 2 of 22 planned lessons are live. New ones are added every week.
Unit 1: Basics
Points, lines, planes and angles.
Points, Lines and Planes
Coming soonAngle Relationships
Ready · 17 minParallel Lines and Transversals
Coming soonMidpoint and Distance Formulas
Coming soonUnit 2: Triangles
The strongest shape.
Triangle Angle Sum
Coming soonTriangle Congruence (SSS, SAS, ASA, AAS)
Coming soonIsosceles and Equilateral Triangles
Coming soonThe Triangle Inequality
Coming soonUnit 3: Similarity and Right Triangles
Same shape, different size.
Similar Triangles
Coming soonThe Pythagorean Theorem
Ready · 18 minSpecial Right Triangles
Coming soonSine, Cosine and Tangent
Coming soonUnit 4: Circles
Round and round.
Parts of a Circle
Coming soonArc Length and Sectors
Coming soonInscribed Angles
Coming soonUnit 5: Area and Volume
Flat space and filled space.
Area of Polygons
Coming soonArea and Circumference of Circles
Coming soonVolume of Prisms and Cylinders
Coming soonVolume of Cones, Pyramids and Spheres
Coming soonUnit 6: Transformations
Slide, flip, turn, resize.
Translations, Reflections and Rotations
Coming soonDilations
Coming soonUnit 7: Proof
Say why it is true.