HSG-CO.C.9

Prove theorems about lines and angles. Theorems include: vertical angles are congruent; when a transversal crosses parallel lines, alternate interior angles are congruent and corresponding angles are congruent; points on a perpendicular bisector of a line segment are exactly those equidistant from the segment's endpoints.

 
48 Lesson(s)
   

PTA (Parallel Lines, Transversals and Angles)

Geometry » Unit: Line-sanity!
Geometry » Unit: Line-sanity!
Stephanie Conklin
Saratoga Springs, NY
Environment: Suburban
 
Big Idea:

Students will draw and measure to discover relationships of angles formed by parallel lines cut by a transversal.

 
Favorites (20)
 
Resources (20)
 
Reflections (1)
parallel wires pta lesson
   
Geometry » Unit: Transformations
Beth Menzie
Amsterdam, NY
Environment: Urban
 
Big Idea:

Name that transformation! Students will work at identifying transformations performed upon geometric figures.

 
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Resources (22)
 
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image name transformation
   

Parallel Lines Intersected by a Transversal

Geometry » Unit: Introduction to Geometric Proofs
Geometry » Unit: Introduction to Geometric Proofs
Marisa Laks
New York, NY
Environment: Urban
 
Big Idea:

Students will build on prior knowledge about the relationships between angles and parallel lines to write formal proofs.

 
Favorites (9)
 
Resources (20)
 
Reflections (3)
parallel lines student work resized for lesson image
   

Intersection Logic

Geometry » Unit: Dimension and Structure
Geometry » Unit: Dimension and Structure
Tom Chandler
Ault, CO
Environment: Rural
 
Big Idea:

Using conjectures about intersections to justify a claim: students find the right argument to make their case.

 
Favorites (1)
 
Resources (28)
 
Reflections (2)
intersectionlogic image
   

Algebra and Angle Pairs

Geometry » Unit: Tools of Geometry
Geometry » Unit: Tools of Geometry
Beth Menzie
Amsterdam, NY
Environment: Urban
 
Big Idea:

More basics of Geometry: Drawing diagrams, identifying and naming angles and angle pairs, and solving algebraic problems involving angle pairs. And an answer to that eternal question - why can't we just measure instead of doing constructions?

 
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Resources (16)
 
Reflections (1)
image basics of coord geom
   

Recyled Definitions

Geometry » Unit: Introducing Geometry
Geometry » Unit: Introducing Geometry
Jessica Uy
Sunnyvale, CA
Environment: Suburban
 
Big Idea:

Given a set of definitions, students will try to find counterexamples while applying their understanding of basic geometry vocabulary, particularly types of angles.

 
Favorites (1)
 
Resources (9)
recycled definitions li cropped
   

Who's a Widget? Making Sense of Definitions

Geometry » Unit: Introducing Geometry
Geometry » Unit: Introducing Geometry
Jessica Uy
Sunnyvale, CA
Environment: Suburban
 
Big Idea:

Students will write precise definitions based on examples and non-examples and test these definitions by looking for counterexamples.

 
Favorites (3)
 
Resources (19)
 
Reflections (2)
widget li resized
   

Parallel Lines Challenge Problem

8th Grade Math » Unit: Transformations
8th Grade Math » Unit: Transformations
Christa  Lemily
Bowling Green, KY
Environment: Suburban
 
Big Idea:

Challenge students to prove what they know about parallel lines and angle relationships when the diagram is unique and exact angle measures irrelevant.

 
Favorites (3)
 
Resources (12)
 
Reflections (1)
parallel lines challenge activity lesson image
   

Proofs about Angles

Geometry » Unit: Introduction to Geometric Proofs
Geometry » Unit: Introduction to Geometric Proofs
Marisa Laks
New York, NY
Environment: Urban
 
Big Idea:

Students will apply postulates to write two column proofs using vertical angles, complementary angles and supplementary angles.

 
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Resources (16)
 
Reflections (1)
angles image
   

Proofs using Postulates

Geometry » Unit: Introduction to Geometric Proofs
Geometry » Unit: Introduction to Geometric Proofs
Marisa Laks
New York, NY
Environment: Urban
 
Big Idea:

Students will explore the equality postulates used in geometric proofs.

 
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Resources (17)
 
Reflections (1)
proofs using postulates li
   

An Introduction to Proof and Parallel Lines

Geometry » Unit: Parallel Lines
Geometry » Unit: Parallel Lines
Beth Menzie
Amsterdam, NY
Environment: Urban
 
Big Idea:

Students are introduced to the two-column proof, and put this knowledge to work on vertical angles and the angle pairs created by parallel lines and transversals.

 
Favorites (4)
 
Resources (24)
 
Reflections (1)
image parallel lines 1
   

Proving It

Geometry » Unit: Line-sanity!
Geometry » Unit: Line-sanity!
Stephanie Conklin
Saratoga Springs, NY
Environment: Suburban
 
Big Idea:

This lesson begins to builds students understanding of proofs using Algebra and Geometry.

 
Favorites (8)
 
Resources (25)
 
Reflections (2)
prove it image
   

Angle Chase Justification

Geometry » Unit: Discovering and Proving Angle Relationships
Geometry » Unit: Discovering and Proving Angle Relationships
Jessica Uy
Sunnyvale, CA
Environment: Suburban
 
Big Idea:

By working several different students, focusing on justification, and revising work after giving and receiving peer feedback, students will justify their reasoning about vertical angles and angles formed by parallel lines.

 
Favorites (6)
 
Resources (20)
angle chase picture resized
   

Angles of a Triangle

Geometry » Unit: Parallel Lines
Geometry » Unit: Parallel Lines
Beth Menzie
Amsterdam, NY
Environment: Urban
 
Big Idea:

Students learn about the different types of triangles, the relationships between the interior and exterior angles of a triangle, and apply their knowledge to numerical problems and constructions.

 
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Resources (23)
 
Reflections (1)
image triangles
   

Now Angles

Geometry » Unit: Introduction to Geometry: Points, Lines, Planes, and Angles
Geometry » Unit: Introduction to Geometry: Points, Lines, Planes, and Angles
Stephanie Conklin
Saratoga Springs, NY
Environment: Suburban
 
Big Idea:

Learn to be like Euclid in this lesson that’s all about measuring, constructing and apply concepts of angles.

 
Favorites (10)
 
Resources (18)
 
Reflections (1)
protracturtle image
Common Core Math
 
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