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Lesson Plan
Curated OER

Congruent Triangles

For Teachers 9th - 12th
Students explore the concept of congruent triangles.  For this congruent triangles lesson, students use Cabri Jr. to construct two congruent triangles using circles.  Students determine if the two triangles are congruent by using the...
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Lesson Plan
Curated OER

Finding the Area of an Equilateral Triangle

For Teachers 9th - 11th Standards
The problem seems simple: find the area of the equilateral triangle whose sides are each length 1. In fact, this same problem is solved in 8th grade, addressing a different Common Core standard, using the formula for area of a triangle...
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Lesson Plan
Curated OER

Exploring Characteristics Needed to Prove Two Trianlges Congruent

For Teachers 10th
Tenth graders explore congruent triangles.  In this geometry lesson, 10th graders investigate the conditions necessary to prove two triangles congruent.  The lesson combines dry erase board activities and the use of technology.
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Lesson Plan
Curated OER

Corresponding Parts of Congruent Triangles

For Teachers 9th - 10th
Students identify different parts of a triangle. In this geometry lesson plan, students differentiate between similar and congruent triangles. They use the navigator to crate a visual of the different parts of a triangle.
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Lesson Plan
Everyday Mathematics

Mathematics Within: Slope and Triangles

For Teachers 8th - 10th Standards
Learners discover a method for determining the slope of a line by creating and comparing similar triangles. They fold coordinate grids to make three similar triangles then measure the sides to compare the relationships between the...
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Activity
Noyce Foundation

Lyle's Triangles

For Students K - 12th Standards
Try five problems on triangles. Levels A and B focus on shapes that can be created from right triangles. Level C touches upon the relationship between the area of a six-pointed star and the area of each triangle of which it is composed....
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Lesson Plan
Curated OER

Congruent Triangles

For Teachers 9th - 12th Standards
Students identify properties of triangles. In this geometry instructional activity, 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

Similar and Congruent Triangles

For Teachers 2nd - 4th
Learners create and classify different types of triangles using an online geo-board. They explore the concepts of similar and congruent as they discover how to draw similar and congruent triangles.
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Lesson Plan
Curated OER

Analyzing Congruence Proofs

For Teachers 9th - 12th Standards
Looking at numerous examples of triangles, each with different properties, geometers develop their understanding of congruency. They use the notation of a counter-example to disprove certain conjectures and prove geometric theorems and...
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Lesson Plan
EngageNY

Congruence Criteria for Triangles—ASA and SSS

For Students 9th - 10th Standards
How do you know if a pair of triangles are congruent? Use the lesson to help class members become comfortable identifying the congruence criteria. They begin with an exploration of ASA and SSS criteria through transformations and...
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Lesson Plan
EngageNY

Base Angles of Isosceles Triangles

For Students 9th - 10th Standards
Build confidence in proofs by proving a known property. Pupils explore two approaches to proving base angles of isosceles triangles are congruent: transformations and SAS. They then apply their understanding of the proof to more complex...
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Lesson Plan
West Contra Costa Unified School District

Investigating Similar Triangles

For Teachers 9th - 12th
Let your use of the resource be in proportion to its usefulness. Pupils investigate similar triangles by measuring side lengths and considering given angle measures. The results of the investigation help develop generalizations about...
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Lesson Plan
Curated OER

Congruent Triangles

For Teachers 10th
Tenth graders explore congruent triangles.  In this geometry lesson, 10th graders investigate the conditions necessary to prove two triangles are congruent by SSS, ASA, AAS, or SAS. 
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Lesson Plan
EngageNY

Definition of Congruence and Some Basic Properties

For Students 8th Standards
Build a definition of congruence from an understanding of rigid transformations. The lesson asks pupils to explain congruence through a series of transformations. Properties of congruence emerge as they make comparisons to these...
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Assessment
Concord Consortium

Isosceles Triangle Spaces

For Students 7th - 10th Standards
How many different types of triangles can your class name? A discovery lesson guides learners through an exploration of the different triangle types and the relationships between their angles and sides. Using coordinate geometry,...
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Unit Plan
1
1
EngageNY

Congruence, Proof, and Constructions

For Teachers 8th - 10th Standards
This amazingly extensive unit covers a wealth of geometric ground, ranging from constructions to angle properties, triangle theorems, rigid transformations, and fundamentals of formal proofs.  Each of the almost-forty lessons is broken...
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Lesson Plan
Curated OER

Triangle Midsegment

For Teachers 9th - 12th Standards
Learn how to calculate the length and midsegments of triangles. Students differentiate between similar and congruent triangles. They create a spreadsheet with their findings.
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Lesson Plan
Curated OER

Building Congruent Triangles

For Teachers K - 12th
Students differentiate between congruent and similar triangles. In this geometry instructional activity, students identify the lengths and angle measures of triangles. They use postulates to prove their answers.
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Lesson Plan
EngageNY

More on the Angles of a Triangle

For Students 8th Standards
Angles and triangles: they're all connected. Uncover the connections between angles in triangles. Scholars learn how to find both exterior and interior angle measures in triangles. The lesson emphasizes the vocabulary related to these...
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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 plan, students differentiate between congruent and similar. They create shapes online and drag those shapes around to create visuals of triangles.
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Lesson Plan
Curated OER

When Does SSA Work to Determine Triangle Congruence?

For Teachers 9th - 10th Standards
Your learners will make good use of the Socratic method in a collaborative task that begins with an assumed solution and ends with deeper understanding of the idea of determining two triangles congruent.
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Unit Plan
1
1
Mathematics Vision Project

Similarity and Right Triangle Trigonometry

For Teachers 10th - 12th Standards
Starting with similar triangles and dilation factors, this unit quickly and thoroughly progresses into the world of right triangle features and trigonometric relationships. Presented in easy-to-attack modules with copious application...
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Lesson Plan
Curated OER

Similar Triangles - Applied Problems

For Teachers 9th - 12th
Students differentiate between similar and congruent triangles. In this geometry lesson plan, students identify the angles of triangles using the similarity theorem. They apply concepts of triangles to the real world.
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Lesson Plan
Curated OER

Nested Similar Triangles

For Teachers 9th - 12th Standards
Nested triangles have been created so that they share a common vertex and vertex angle. Learners drag the endpoints of the side that is opposite the common angle to discover the conditions that make the nested triangles similar. When...

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