Learning Goal
Make geometric constructions
Teacher tools for this standard
Lesson Plan · Guided Notes · Exit Ticket · Re-teach · Homework
Teacher tools for this standard
Lesson Plan · Guided Notes · Exit Ticket · Re-teach · Homework
- Lesson Plan →Objectives, pacing and practice, built from this lesson's brief.
- Guided Notes →One page your students fill in and keep.
- Exit Ticket →Three items at the end of class. No student accounts.
- Re-teach →After an exit ticket: who missed what, and what to do tomorrow.
- Homework →Assign practice; it grades itself.
**HSG.CO.D.12**: Make formal geometric constructions with a variety of tools and methods (compass and straightedge, string, reflective devices, paper folding, dynamic geometric software, etc.). Copying a segment; copying an angle; bisecting a segment; bisecting an angle; constructing perpendicular lines, including the perpendicular bisector of a line segment; and constructing a line parallel to a given line through a point not on the line.
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HSG.CO.D.12: Make formal geometric constructions with a variety of tools and methods (compass and straightedge, string, reflective devices, paper folding, dynamic geometric software, etc.). Copying a segment; copying an angle; bisecting a segment; bisecting an angle; constructing perpendicular lines, including the perpendicular bisector of a line segment; and constructing a line parallel to a given line through a point not on the line.
What you'll learn
- Perform the six fundamental compass-and-straightedge constructions: copy a segment, copy an angle, bisect a segment, bisect an angle, construct a perpendicular line (including the perpendicular bisector), and construct a line parallel to a given line through an external point
- Explain why each construction works by connecting the steps to properties of circles, congruent triangles, and symmetry
- Distinguish between a formal geometric construction (using only compass and straightedge) and a drawing or measurement-based sketch
- Use alternative construction tools and methods, including string, reflective devices, paper folding, and dynamic geometry software such as GeoGebra
- Justify that each construction produces the intended result by referencing precise geometric definitions and properties
Slides
Step through the lesson, or watch it as a narrated video • 2 slide decks
Formal constructions intro copying bisecting
✓ Start hereFormal constructions perpendicular parallel synthesis
Practice
Try it on your own