Geometry Grades 9 to 12
Build a full Geometry year in the Scene Shop: transformations, congruence, proof, similarity, trigonometry, circles, coordinates and volume, every answer checked.
Free, start to finish. No card. Every week opens without signing in.
- Grade
- Grades 9 to 12
- Length
- 12 weeks
- Pace
- 6 short lessons a week, about 20 minutes each
- Price
- Free, every week
About this course
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.
Kids will
- 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
The 12 weeks
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Week 1
Points, Lines and the Chalk Grid
Precise words and string-and-chalk constructions
CCSS G-CO.A.1, G-CO.D.12, G-CO.D.13
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Week 2
Rigid Motions and Symmetry
The flats slide, flip and turn
CCSS G-CO.A.2, G-CO.A.3, G-CO.A.4, G-CO.A.5
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Week 3
Congruence from Rigid Motions
Two braces match when a sequence of motions carries one onto the other
CCSS G-CO.B.6, G-CO.B.7, G-CO.B.8
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Week 4
Proofs about Lines, Angles, Triangles and Parallelograms
The parallelogram frame earns its name
CCSS G-CO.C.9, G-CO.C.10, G-CO.C.11
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Week 5
Dilations and Similarity
The scale model and the flashlight
CCSS G-SRT.A.1, G-SRT.A.2, G-SRT.A.3
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Week 6
Similar Triangles and Proof
Shadows, side-splitters and the altitude
CCSS G-SRT.B.4, G-SRT.B.5
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Week 7
Right Triangles and Trigonometry
The ramp, the cable and the angle finder
CCSS G-SRT.C.6, G-SRT.C.7, G-SRT.C.8
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Week 8
Circles
The turntable and the spotlight
CCSS G-C.A.1, G-C.A.2, G-C.A.3, G-C.B.5
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Week 9
Coordinates: Lines, Segments and Figures
The taped stage grid
CCSS G-GPE.B.4, G-GPE.B.5, G-GPE.B.6, G-GPE.B.7
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Week 10
Equations of Circles and Parabolas
The turntable and the lamp dish on the stage grid
CCSS G-GPE.A.1, G-GPE.A.2
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Week 11
Volume: Where the Formulas Come From
Paint, foam and a jug of water
CCSS G-GMD.A.1, G-GMD.A.3, G-GMD.B.4
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Week 12
Modeling the Set and Opening Night
Every prop a shape, every plan a number
CCSS G-MG.A.1, G-MG.A.2, G-MG.A.3
Try Week 1 today.
Open the course, pick Day 1 and go. Make a free parent account when you want progress saved for each kid.