CCSS.Math.Content.HSG-CO.D

CCSS.Math.Content.HSG-CO.D is a cluster heading. These are the individual standards under it.

• CCSS.Math.Content.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 ...

• CCSS.Math.Content.HSG-CO.D.13

  Construct an equilateral triangle, a square, and a regular hexagon inscribed in a circle.

01

What Students Need to Do

Students use a compass and straightedge to create exact lines, angles, and regular figures. They follow a sequence of arcs and intersections rather than relying on measurement.

02

What Mastery Looks Like

Students produce accurate bisectors, perpendicular lines, parallel lines, and regular figures with a compass and straightedge. They keep construction marks visible and explain how the arcs determine each result.

03

Common Misconceptions

Students often measure or eyeball instead of using intersecting arcs. They may change the compass width too soon, choose the wrong arc intersection, or erase marks that show their reasoning.

04

How to Assess It

Give students an angle and ask them to construct its bisector using only a compass and straightedge. Require all arcs and intersection points to remain visible.

1. 01

   Give students a compass, straightedge, and line segments to copy, bisect, and use when building perpendicular lines.

2. 02

   Ask students to write: "Why do equal-radius arcs locate a perpendicular bisector without measuring?"

3. 03

   Run a construction relay where teams complete cards for angle bisectors, perpendiculars, parallels, and regular polygons, then check one another's work.

4. 04

   Have students design a repeating tile pattern by constructing an equilateral triangle, square, or regular hexagon without using a ruler's measurements.

• CCSS.Math.Content.HSG-CO.C

  Prove geometric theorems

• CCSS.Math.Content.HSG-MG.A.3

  Apply geometric methods to solve design problems (e.g., designing an object or structure to satisfy physical constraints or minimize cost; working with typograp...

• CCSS.Math.Content.HSG-MG.A

  Apply geometric concepts in modeling situations