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Lesson Plan
Illustrative Mathematics

Sum of Angles in a Polygon

For Teachers 8th - 12th Standards
How can learners use algebra to solve a geometry problem? Help learners create an equation that shows the relationship between the number of sides of a polygon and the sum of the interior angles. Students are asked to divide the...
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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

Tile Patterns II: Hexagons

For Teachers 7th - 9th Standards
After learning that the sum of interior angles for triangles is 108 degrees, take it further to show that the sum of angles in any polygon is the same! Using hexagons, pupils practice finding the measure of the six congruent angles. Make...
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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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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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Worksheet
Curated OER

Geometry - Angles Overview

For Students 7th - 8th
Learners address 14 questions that include naming all pairs of opposite and supplementary angles for sets of intersecting lines and then, finding the measure of the unknown angle. They determine the measure of the angle that is...
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Lesson Plan
Hotchalk

Triangle Sum Theorem

For Teachers 8th - 10th Standards
Your visual geometry learners will appreciate triangle drawings as they model the triangle sum theorem and algebraically solve to find the missing interior angle in a triangle. Practice problems increase in complexity and vary in their...
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Lesson Plan
Curated OER

Angle Relationships

For Teachers 9th - 10th
Students investigate geometric relationship using conjecture about linear pairs and vertical angles. For this geometry lesson, students apply their theorems and previous geometry knowledge to solve for and find angles of linear pairs....
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Worksheet
Curated OER

Angles Activities

For Students 5th - 8th
A series of geometry worksheets have mathematicians constructing, dissecting, overlapping, and measuring as they analyze angles in various contexts. Learners use symmetry and reflections in a compass rose to write instructions on...
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Lesson Plan
Mathematics Assessment Project

Identifying Similar Triangles

For Teachers 7th - 9th Standards
Math whizzes work with angle sums and exterior angles to figure out the measure of other angles. This particular publication provides comprehensive support in the form of an anticipatory activity, questions designed to prompt discussion,...
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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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Worksheet
Kuta Software

Polygons and Angles

For Students 6th - 10th
Get out those protractors! Geometers measure interior and exterior angles of 10 polygons, including a 24-gon. They also calculate the interior angle sum of the polygons. 
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Workbook
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University of Utah

Geometry: Angles, Triangles, and Distance

For Students 8th Standards
The Pythagorean Theorem is a staple of middle school geometry. Scholars first investigate angle relationships, both in triangles and in parallel lines with a transversal, before proving and applying the Pythagorean Theorem.
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Lesson Plan
Curated OER

Geometry In Space

For Teachers 9th - 12th
How can we identify shapes in the Universe? High schoolers will compare and contrast elliptic and hyperbolic geometry. They will also explore one possible way to measure the curvature of the Universe, namely, by measuring the sum of the...
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Lesson Plan
EngageNY

Unknown Angle Proofs—Proofs of Known Facts

For Teachers 9th - 10th Standards
Lead the class in a Greek history instructional activity with a geometric twist. Pupils relate a short video about geometric properties to modern-day methods of solving for unknown angles. They discuss parallel line theorems and complete...
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Lesson Plan
EngageNY

Solve for Unknown Angles—Angles in a Triangle

For Teachers 9th - 10th Standards
Assist your class with each angle of geometry as they use exterior angles to form linear pairs with adjacent interior angles. They cover multiple vocabulary terms and work practice problems, complete with justifications, before taking an...
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Lesson Plan
EngageNY

Angle Sum of a Triangle

For Students 8th Standards
Prove the Angle Sum Theorem of a triangle using parallel line and transversal angle relationships. Pupils create a triangle from parallel lines and transversals. They find angle measures to show that the angles of a triangle must total...
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Lesson Plan
Curated OER

Tile Patterns I: Octagons and Squares

For Teachers 7th - 9th Standards
This can be used as a critical thinking exercise in congruence or as a teaching tool when first introducing the concept. Four octagons are arranged in such a way that a square is formed in the middle. With this information, geometry...
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Worksheet
Curated OER

Geometry

For Students 6th - 10th
In this geometry activity, students find the sum of angles, label angles, and more. Students complete 6 questions total on this activity.
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Worksheet
Lone Star College

Geometry Worksheet II

For Students 7th - 10th Standards
Young geometers get practice with the algebra of angles in an extensive skills practice worksheet. Supplementary, complementary, and vertical angle relationships are used, along with parallel lines cut by a transversal and angle sum of a...
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Lesson Plan
Virginia Department of Education

Angles in Polygons

For Teachers 9th - 11th
Polygons — it's all about the angles. Groups work with dynamic geometry software to find the sum of the measures of the angles of various polygons. After finding the information for several polygons, the groups generate a formula that...
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Worksheet
Geometry Accelerated

Accelerated Geometry Review Sheet

For Students 8th - 10th Standards
Your geometry learners use their knowledge of various geometric concepts to write proofs. Starting with givens containing parallel line segments with transversals and triangles and quadrilaterals, and the mid-point and distance formulas;...
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Worksheet
Curated OER

Sum of Interior Angles

For Students 10th
For this sum of interior angles worksheet, 10th graders solve 10 different problems that are related to determining the sum of various interior angles in figures. First, they determine the sum of the interior angles of a dodecagon. Then,...
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Worksheet
Curated OER

Angle Bisectors

For Students 10th
In this angle bisector worksheet, 10th graders solve and complete 23 various types of geometry problems. First, they find the angles listed in the figure shown. Then, students determine the sum of the interior angles of a polygon. They...