math Grades 9 to 12 Live now

Geometry Grades 9 to 12

Geometry Grades 9 to 12 is a 12-week high-school geometry course. Students join Comet and Wren in the Scene Shop, the workshop behind a community theater, as the crew designs and builds the set for the spring show, and every week's geometry makes a piece of the set work. The course covers precise definitions and constructions, rigid motions and symmetry, triangle congruence from rigid motions, proofs about lines, angles, triangles and parallelograms, dilations and similarity, similar triangles and proportion, right-triangle trigonometry, circles and their angles, arcs and sectors, coordinate geometry including the equation of a circle, where volume formulas come from and how to use them, and geometric modeling with density and design. Every week lists the Common Core high-school geometry standards it practices. Short daily lessons with checked answers, a hands-on Shop Lab build each week and a Saturday Shop Day for the family. No accounts, apps or software needed. 100% free, start to finish.

• Use precise definitions and compass-and-straightedge constructions to describe and build figures
• Describe translations, reflections and rotations, and use them to decide when two figures are congruent
• Prove theorems about lines, angles, triangles and parallelograms, and explain each step
• Use dilations and similar triangles, including the trigonometric ratios, to find lengths and angles
• Work with circles, their angles, arcs and sectors, and the equations of circles and parabolas
• Explain volume formulas, use them to solve problems and model real objects with geometry