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Lesson Plan
Curated OER

Triangle's Interior Angles

For Teachers 7th - 9th Standards
Given a pair of parallel lines and a triangle in between, geometers prove that the sum of the interior angles is 180 degrees. This quick quest can be used as a pop quiz or exit ticket for your geometry class.
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Lesson Plan
Curated OER

Alternate Interior Angles

For Teachers 9th - 12th Standards
Label angles of parallel lines to analyze the angles created by a transversal and two parallel lines. They graph their lines and observe the similarity and difference in the angles.
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Worksheet
Curated OER

Geometry Lines and Angles

For Students 10th
In this lines and angles worksheet, 10th graders solve and complete types of problems that include different line segments and angles to identify. First, they determine whether each line is parallel, skew, or perpendicular in the diagram...
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Worksheet
Curated OER

Challenge: Skills and Applications Lesson 3.3

For Students 9th - 12th
In this angle measures worksheet, students solve 9 short answer problems. Students find values for x and y given two parallel lines cut by a transversal. Students use alternate interior, supplementary, and exterior angles to find x and y.
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Lesson Plan
EngageNY

Looking More Carefully at Parallel Lines

For Students 9th - 10th Standards
Can you prove it? Making assumptions in geometry is commonplace. This resource requires mathematicians to prove the parallel line postulate through constructions. Learners construct parallel lines with a 180-degree rotation and then...
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Lesson Plan
Willow Tree

Angles Formed by Transversals of Coplanar Lines

For Students 8th - 11th Standards
Create a strong understanding of the relationships formed when parallel lines intersect a transversal. Discuss each type of angle pair and their relationship to each other. 
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Activity
Illustrative Mathematics

Find the Missing Angle

For Teachers 7th - 9th Standards
This one activity requires young geometers to pull together information they are currently learning with things they have learned previously. Here they rely on understanding something about parallel lines, alternative interior angles,...
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Worksheet
Curated OER

Geometry: Angles

For Students 11th - 12th
In this angle worksheet, students find the value for a given variable. They use similar figures, alternate interior angles, side angle side, and other geometric theorems and proofs to determine the value of the given variable. This...
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Interactive
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GeoGebra

Conjectures and Proof

For Students 9th - 12th Standards
Transform proofs using triangle rotations. By rotating a triangle around various points, class members develop proofs. Participants prove relationships of alternative interior angles formed by parallel lines and the sum of the interior...
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Instructional Video14:56
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2
Flipped Math

Lines and Angles

For Students 9th - 12th Standards
Develop a sense of understanding. Pupils learn eight definitions dealing with types of lines and angles formed when two lines are crossed by another line. Learners use the definitions to identify the lines and pairs of angles in figures...
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Interactive
CK-12 Foundation

Proofs: Angle Pairs and Segments—The Three Angle Problem

For Students 9th - 11th
Finding the sum of the measures of three angles is easy, unless you have no clue what the measures are. Learners use an interactive diagram to see a geometric problem in a different way. A set of challenge questions takes them through...
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Lesson Plan
Virginia Department of Education

Lines and Angles

For Teachers 9th - 11th Standards
Explore angle relationships associated with transversals. Pupils construct parallel lines with a transversal and find the measures of the angles formed. They figure out how the different angles are related before constructing...
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Lesson Plan
Curated OER

Geometric Angles

For Teachers 8th - 10th
Students explore angles and their use in Geometry. Students investigate three different kinds of angles: obtuse, acute, and right angles through an online activity. They identify pairs of angles with special relationships: vertical,...
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Assessment10:41
Mathed Up!

Angles: Parallel Lines

For Students 9th - 11th Standards
Viewers are presented with seven problems with parallel lines and angle relationships and must use the given information to find the measures of specific angles. To finish, they explain their process in finding the measures in the problems.
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Worksheet
Curated OER

Twenty-Eight Parallel Lines with a Transversal Problems

For Students 9th - 10th
In this parallel lines with a transversal worksheet, students identify angles as corresponding, alternate interior, or alternate exterior, find the measure of angles, and solve for indicated values.  The solutions are provided.
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Worksheet
Curated OER

Geometry Angles

For Students 10th
For this geometry angles worksheet, 10th graders find and solve 22 problems related to determining the measure of various angles. First, they determine the measure of each angle in the first figure if lines p and q are parallel. Then,...
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Worksheet
Curated OER

Properties of Angles, Lines, and Triangles

For Students 10th
In this properties of angles, lines and triangles worksheet, 10th graders solve and complete 28 different problems that include determining the measurement of various figures shown. First, they use the geometric properties and theorems...
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Lesson Plan
EngageNY

Similarity and the Angle Bisector Theorem

For Teachers 9th - 10th Standards
Identifying and verifying reproducible patterns in mathematics is an essential skill. Mathematicians identify the relationship of sides when an angle is bisected in a triangle. Once the pupils determine the relationship, they prove it to...
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Lesson Plan
EngageNY

Unknown Angle Proofs—Proofs with Constructions

For Teachers 9th - 10th Standards
Provide your emerging mathematicians with the tools to learn as they incorporate auxiliary lines to solve unknown angle proofs in this continuing segment. They decipher information from a diagram to uncover the missing pieces and...
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Lesson Plan
West Contra Costa Unified School District

Parallel Lines Cut by a Transversal

For Teachers 9th - 12th
Parallel lines seem so right for each other. It's too bad they'll never, ever meet. Learners use tracing paper to discover relationships among angles formed by two parallel lines cut by a transversal. They apply this information to find...
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Lesson Plan
Curated OER

Angles and Transversals

For Teachers 9th - 12th Standards
Pupils explore the concept of angles and transversals. They construct parallel and non-parallel lines cut by a transversal using Cabri Jr. Learners then determine which angles are congruent and the relationship of angles when two lines...
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Instructional Video11:40
2
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Flipped Math

Properties of Parallel Lines

For Students 9th - 12th Standards
Work within a parallel universe. Scholars learn about the relationships of angles when two parallel lines are intersected by a transversal. They see how to find the measurements of all eight angles by knowing the measure of one angle....
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Handout
El Paso Community College

Geometry Definitions

For Students 7th - 9th Standards
Geometry is full of shapes, figures, and corresponding things here and there. The guide shares all of the key pieces of geometric information in a nicely color-coded and labeled sheet. 
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Lesson Plan
EngageNY

Solve for Unknown Angles—Transversals

For Teachers 9th - 10th Standards
Lead your class on an exciting journey through the world of math as they review geometry facts and solve for unknown angles. They learn how to use auxiliary lines and congruent angles to correctly complete each practice problem...