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Lesson Plan
Curated OER

Triangle Puzzler

For Teachers 5th - 8th
Students are introduced to some basic concepts of geometry. They explain that the definition of a triangle is a figure with three sides, three angles, and three points. Triangles can be named by using three points in their correct sequence.
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Lesson Plan
Curated OER

Tennis Triangle

For Teachers 9th - 12th
Learners calculate the height of a tree or flagpole. They measure the shadow of the tree or flagpole and the length of a shadow of a meterstick. Using similar triangles, calculate the heigh. Devise two additional ways in which to measure...
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Worksheet
Curated OER

Proofs

For Students 8th - 11th
In this geometric proof worksheet, students compose 20 triangle congruency proofs. Students will decide if there is enough information in problems 1-6 to prove if any triangles are congruent. In problems 17 to 20, students use given...
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Lesson Plan
West Contra Costa Unified School District

Law of Sines

For Teachers 9th - 12th Standards
Laws are meant to be broken, right? Learners derive the Law of Sines by dropping a perpendicular from one vertex to its opposite side. Using the Law of Sines, mathematicians solve for various parts of triangles.
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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
Willow Tree

Common Geometric Figures

For Students 8th - 11th Standards
Geometry could be called the study of figures. An overview of the figures found in a typical geometry course contains a study of different triangles, quadrilaterals, and regular polygons. 
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Worksheet
Curated OER

The Premises of Geometry

For Students 9th - 10th
In this geometry worksheet, students solve for missing midpoints, segments and angles using algebraic equations. They use geometric properties to solve these equations. There are 32 questions on 7 different worksheets.
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Lesson Plan
Curated OER

Angles in Triangles

For Teachers 8th
Eighth graders translate word problems using mathematical ideas. For this geometry lesson, 8th graders identify angles of triangles using equations and the triangle sum theorem. They create angles with a protractor and straight edge.
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Lesson Plan
Curated OER

Triangle Exterior Angles Theorem

For Teachers 7th - 9th
Students identify the measure of missing exterior angles. For this geometry lesson,students define and apply the exterior angle theorem to solve problems. They use Cabri software to create different angles and make investigations.
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Worksheet
Curated OER

Angles

For Students 6th - 8th
In this math learning exercise, students measure a series of angles. Then they measure the angles in the triangles and determine the sum of the angles.
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Lesson Plan
Curated OER

Geometry w/o Figures - Week 7 (Basic Geometry Formulas)

For Teachers 10th - 12th
In this basic geometry worksheet, students use basic formulas of geometry to find the area of a polygons, the number of sides of a polygon, and sum of the angles of various polygons. This three-page worksheet contains eight problems.
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Worksheet
Curated OER

Interior and Exterior Angles of Polygons

For Students 10th
In this angles of polygons learning exercise, 10th graders solve and complete 18 different problems that include determining various interior and exterior angles. First, they determine the measure of various angles described in the first...
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Lesson Plan
Curated OER

Why Does ASA Work?

For Teachers 9th - 10th Standards
Your geometry learners explore Angle-Side-Angle congruence in this collaborative task. The sum of the interior angles of all triangles being one hundred eighty degrees, is the key learners will discover as they explain their reasoning...
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Lesson Plan
Curated OER

The Distance to an Unapproachable Point

For Teachers 8th - 11th
Students use geometry or trigonometry to measure the distance of a far off point. They verify their measurements using a tape measure to check their work.
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Lesson Plan
Curated OER

Pythagorean Theorem

For Teachers 7th - 10th
Learners find the different ratios of a triangle. In this geometry lesson, students use the Pythagorean Theorem to solve for missing sides and angles on a right triangle. They use a robot to create a right triangle.
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Interactive
Curated OER

Arcs and Chords Multiple Choice

For Students 9th - 10th
In this geometry worksheet, learners answer questions about triangles using the correct properties. They find missing angles and sides of triangles. There are 15 questions with an answer key.
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Lesson Plan
EngageNY

Similarity

For Teachers 8th Standards
Use the coordinate plane to show two figures are similar. The lesson incorporates congruence transformations and dilations to move a figure on to another figure. Pupils determine that if a similarity transformation exists between two...
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PPT
Curated OER

Chalkboard Challenge: Fifth Grade Math Review

For Teachers 4th - 5th
This PowerPoint addresses fifth grade math concepts, focusing mostly on geometry. The interactive math review game is in a "Jeopardy" style format and enables students to revisit the topics in geometry such as polygons, quadrilaterals...
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Lesson Plan
Curated OER

Transformations and Rotations

For Teachers 9th - 12th Standards
Students define and identify transformation and rotation. In this geometry lesson, students define rotations as congruence or isometry. They find the coordinates of an image and pre-image.
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Lesson Plan
Curated OER

Symmetries of a Quadrilateral I

For Teachers 9th - 10th Standards
Learners examine the properties of quadrilaterals from the point of view of rigid motion. Different types of quadrilaterals are characterized by their symmetries, so learners explore the symmetries of a described quadrilateral to...
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Unit Plan
Mathematics Vision Project

Circles: A Geometric Perspective

For Teachers 10th - 12th Standards
Circles are the foundation of many geometric concepts and extensions - a point that is thoroughly driven home in this extensive unit. Fundamental properties of circles are investigated (including sector area, angle measure, and...
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Worksheet
Curated OER

Understanding Angles

For Students 9th - 11th
In this geometry worksheet, students identify the different measure of each angle. They rotate the rays around and make observations about the angles formed. There are 15 questions and lots of examples.
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Worksheet
Curated OER

Transformations

For Students 10th
In this geometry worksheet students rotate, reflect, and translate geometric shapes. The four page worksheet contains seventeen problems  Solutions are not provided. 
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Lesson Plan
Curated OER

The Flat Earth

For Teachers 9th - 11th
Students differentiate between different planes. In this geometry lesson, students differentiate between a plane and a sphere. They discuss the Great Circle, Geodesic and Lune as it relates to the earth.