Proofs: Full Unit - Teaching Two-Column Geometry Proofs

Math Giraffe
Grade Levels
9th - 11th
Formats Included
  • Zip (78 (plus answer keys))
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Math Giraffe


Proof Writing in High School Geometry (Two-Column Proofs) - Introduction:

This full unit pack (108 pages including answer keys) has all the resources you need to teach your Geometry students how to write proofs. It begins at the most basic level with the properties and postulates that will later become justifications in their proofs.

The unit teaches the structure and process for writing a proof, beginning with basic algebra proofs. Students get comfortable with substitution and the transitive property before being led into Geometry proofs.

A full presentation in color is included as well as a set of black and white printables with practice, differentiated warm-ups, quizzes, a graphic organizer, blank proof templates, and a puzzle activity. There are plenty of worksheets containing proofs in a variety of difficulty levels. All answer keys are included. A pacing guide is also included.

The presentation pages walk the students through step-by-step and include hints and tips. Please see the preview for more information and sample pages.

The zip file includes a presentation and a set of printables (PDF).

Topics included (justifications used in proofs):

Addition Property of Equality

Subtraction Property of Equality

Multiplication Property of Equality

Division Property of Equality

Reflexive Property (of Equality and Congruence)

Symmetric Property (of Equality and Congruence)

Transitive Property (of Equality and Congruence)

Substitution Property (of Equality and Congruence)

Segment Addition Postulate

Angle Addition Postulate

Definition of Congruence

Definition of Midpoint

Definition of Bisector

Definition of Right Angle

Definition of Perpendicular

Vertical Angles Theorem

Right Angles Theorem

Linear Pair Theorem

Corresponding Angles Postulate

Alternate Interior Angles Theorem (and its Converse)

Alternate Exterior Angles Theorem (and its Converse)

Same-Side Interior Angles Theorem (and its Converse)

Same-Side Exterior Angles Theorem (and its Converse)

Triangle Sum Theorem

Base Angles of Isosceles Triangles Theorem (and its Converse)

This unit goes up to, but does not include congruent triangles.

If students are not already familiar with special angle pairs (complementary, supplementary, vertical angles, etc, you may be interested in this supplementary resource as well:

Lesson Pack: Special Pairs of Angles

If students are not already familiar with transversals, you may be interested in this supplementary resource as well:

Lesson Pack: Transversals

You may also like these other Geometry Resources:

High School Geometry Super Bundle

Geometry Proofs Task Cards

Congruent Triangles Proofs

Total Pages
78 (plus answer keys)
Answer Key
Teaching Duration
2 Weeks
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to see state-specific standards (only available in the US).
Prove theorems about parallelograms.
Prove theorems about triangles.
Prove theorems about lines and angles.


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