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Lesson Plan
Curated OER

Triangle Inequality Theorem

For Teachers 8th - 10th
Students use the inequality theorem to solve triangles and their properties. In this geometry lesson, students are given spaghetti of different lengths and asked to create triangles. They conclude the necessary length needed to make a...
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Lesson Plan
Curated OER

Investigating Trigonometric Ratios Through Similar Right Triangles

For Teachers 9th - 10th
Students identify similar and congruent right triangles. In this geometry instructional activity, students use trigonometric ratios to identify missing sides and angles of a triangle. They differentiate similar and congruent triangles.
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Worksheet
Houghton Mifflin Harcourt

Similar Polygons and Circles

For Students 9th - 12th
In these similar polygons and circles worksheets, students complete 15 questions including 9 word problems regarding similar polygons. Students then complete 15 questions including 1 word problem involving circumference, area, and arc...
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Lesson Plan
Curated OER

Branding Circles, Squares, Rectangles, Triangles

For Teachers K
Compare and classify 2-D shapes! Kindergarteners inspect the attributes of plane shapes and examine shapes in everyday life. They label the circles, squares, rectangles, and triangles they find. This is the website where you can find the...
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Lesson Plan
Discovery Education

Discovering Math: Exploring Geometry

For Teachers 6th - 8th Standards
Apply geometric properties and formulae for surface area and volume by constructing a three-dimensional model of a city. Learners use similar and congruent figures and transformations to create a city of at least 10 buildings. They trade...
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Lesson Plan
Project Maths

Introduction to Trigonometry

For Teachers 9th - 12th Standards
The topic of trigonometric ratios is often covered with loads of rote memorization baked into the activity. This activity set, however, leans more on using similar triangles and discovery learning to help young geometers develop a deeper...
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Interactive
Scholastic

Study Jams! Congruent Figures

For Students 4th - 7th Standards
There is more to congruency than just looking similar. Learn the difference and calculate the matching angles and sides to prove the congruence between figures. Lesson has step-by-step slides and follows with an assessment. 
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Lesson Plan
Curated OER

Angles and Similarity

For Teachers 9th - 12th Standards
Students identify triangles as similar or congruent. In this geometry lesson, students drag triangles around on the navigator to see the effect of different angles on the shape of the triangle. They discuss angle similarity and angle...
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Lesson Plan
Curated OER

Ratios of Similar Figures

For Teachers 9th - 12th Standards
Students identify the ratios of different triangles. In this geometry lesson, students identify the similarity and differences of triangles. They use the navigator to move the sides of the triangle around.
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Lesson Plan
Curated OER

The Sierpinski Triangle

For Teachers 9th - 10th
Students investigate the Sierpinski triangle. In this geometry instructional activity, students define fractal curves and its relationship to triangles. They identify repeating sequences and relate it to fractals.
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Lesson Plan
Curated OER

Similarity and Congruence

For Teachers 9th - 12th
High schoolers explore the concept of similarity and congruence. In this similarity and congruence lesson, students cut out strips of paper and form a triangle. High schoolers try to prove that their triangles are congruent using the SSS...
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Worksheet
Curated OER

Congruent Triangles Homework

For Students 9th - 10th
In this geometry worksheet, students use proofs to solve properties of triangles. They differentiate between congruent and similar triangles. There are 15 questions.
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Lesson Plan
Curated OER

Measuring Heights With Triangles

For Teachers 8th - 10th
Pupils identify the different properties of triangles. In this geometry lesson, students differentiate between congruent and similar triangles. They use mathematical reasoning to solve word problems.
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Worksheet
Curated OER

The Triangles Problem

For Students 10th
In this geometry worksheet, 10th graders explain how two triangles can have 5 parts of the other triangle and still not be congruent. This is a word problem with an answer key.
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Lesson Plan
Curated OER

Congruent Triangles

For Teachers 9th - 12th Standards
Students identify properties of triangles. In this geometry lesson, students differentiate between similar and congruent triangles. They use the umber of sides to help define the angle of the polygon.
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Lesson Plan
Curated OER

Triangle Congruence

For Teachers 9th - 11th
Students use web applet to create congruent triangles. In this geometry lesson, students differentiate between congruent and similar. They create shapes online and drag those shapes around to create visuals of triangles.
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Worksheet
Curated OER

Triangles

For Students 3rd - 4th
In this triangles learning exercise, students identify 3 triangles by the length of their sides and 3 triangles according to their internal angles.
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Lesson Plan
Curated OER

Congruent and Similar figures

For Teachers 8th
Eighth graders explore congruent and similar figures.  In this eighth grade geometry lesson, 8th graders use geoboards to create congruent and similar figures and explore the relationships between the sides and angles. 
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Assessment
EngageNY

End-of-Module Assessment Task: Grade 7 Mathematics Module 6

For Students 7th Standards
Determine the level of understanding within your classes using a summative assessment. As the final lesson in a 29-part module, the goal is to assess the topics addressed during the unit. Concepts range from linear angle relationships,...
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Lesson Plan
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Illustrative Mathematics

Why Does SSS Work?

For Teachers 9th - 10th Standards
While it may seem incredibly obvious to the geometry student that congruent sides make congruent triangles, the proving of this by definition actually takes a bit of work. This exercise steps the class through this kind of proof by...
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Worksheet
Curated OER

Similar Right Triangles-Introductions to Trigonometry

For Students 9th - 10th
For this geometry worksheet, students examine similar right triangles as the basis for the foundation of trigonometry. Students define the basic trigonometric functions and use a calculator to find the trigonometric value of an angle....
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Lesson Plan
Curated OER

Triangles in Architecture

For Teachers 10th - 12th
Learners find triangles in the real world. In this geometry lesson, students analyze and identify properties of two and three-dimensional objects. They differentiate between similarity and congruence.
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Lesson Plan
Curated OER

Similar Triangles - Geometry Exploration

For Teachers 8th
Eighth graders become engaged in a lesson plan in geometry to improve mathematical skills. They construct triangles, segments, and points using Geometer's Sketchpad to demonstrate how dilations of triangles and rectangles change...
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Lesson Plan
Curated OER

Triangles & Congruence, Proportions & Similarity, Right Triangle & Trigonometry

For Teachers 9th - 12th
High schoolers are introduced to the topic of congruence and proportions in Geometry. Using technology, they construct and validate the properties of various geometric figures and identify whether it is congruent or proportion to the...