NY Next Generation Math GEO-G.CO.1
The Standard
Know precise definitions of angle, circle, perpendicular lines, parallel lines, and line segment, based on the undefined notions of point, line, distance along a line, and distance around a circular arc as these exist within a plane.
New York State Next Generation Mathematics Learning Standards
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students use precise geometric definitions built from point, line, distance, and circular-arc distance. They distinguish angle, circle, perpendicular lines, parallel lines, and line segment using necessary conditions.
What Mastery Looks Like
- The student states a precise definition and applies it to examples and nonexamples. The explanation names the undefined ideas on which the definition depends.
Common Misconceptions
- Students may define a figure by appearance or use the term itself in its definition. They may confuse a line segment with its length or parallel lines with merely nonintersecting segments.
How to Assess It
- Show four figures, including a near-miss. Ask students to select one term, write its precise definition, and classify all four figures.
Lesson moves
Ways to Teach It
Build examples and nonexamples with string, points, rulers, and compasses, then refine definitions.
Ask which words in a proposed definition are undefined and which require earlier definitions.
Play definition repair by correcting vague or circular geometry statements.
Write specifications for a drafting program that must draw a precise geometric object.
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Printable GEO-G.CO.1 Worksheet
A ready-to-print activity worksheet aligned to GEO-G.CO.1, with an answer key for the teacher on its own page. No account needed.
PDF, US Letter, prints cleanly in black and white.
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Related Standards
- NY-4.G.1
Draw points, lines, line segments, rays, angles (right, acute, obtuse), and perpendicular and parallel lines. Identify these in two-dimensional figures.
- GEO-G.C.2.b
Identify, describe and apply relationships among radii, chords, tangents, and secants of a circle.
- GEO-G.CO.4
Develop definitions of rotations, reflections, and translations in terms of points, angles, circles, perpendicular lines, parallel lines, and line segments.
- GEO-G.C.2.a
Identify, describe and apply relationships between the angles and their intercepted arcs of a circle.
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