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Lesson Plan
Curated OER

Isosceles Triangle Theorem

For Teachers 8th - 10th
In this geometry worksheet, students differentiate between regular triangles and isosceles triangles. They apply the converse theorem and the vertex angle. There are eleven questions with an answer key.
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Lesson Plan
Curated OER

Study Buddies: Classifying Triangles

For Teachers 4th - 5th
In this math worksheet, pupils analyze an informative chart about the measurement and angles of equilateral, isosceles and scalene triangles. Students then answer 5 questions about classifying triangles.
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PPT
Primary Resources

Different Types of Triangles

For Teachers 4th - 5th Standards
Are there different types of triangles? Yes there are, and this presentation describes each by its properties or characteristics. Right, equilateral, isosceles, and scalene are all shown and defined. The presentation isn't particularly...
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Lesson Plan
Curated OER

Geometric Figures-Triangles

For Teachers 4th
Fourth graders explore triangles. In this math lesson plan, 4th graders discuss the different types of triangles. Students create triangles using wiki sticks. Students complete an online matching game.
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Lesson Plan
Curated OER

Geometry of Triangles - Week 6

For Teachers 10th - 12th
In this triangle worksheet, students explore the characteristics of triangles. They find the area of a pentagon, lengths of the sides of a triangle and the area of a quadrilateral. This two-page worksheet contains seven problems.
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Worksheet
Curated OER

Triangle Designs

For Students 4th - 6th
In this triangles worksheet, students draw different triangles and write how many sides and angles each one has. Students draw 4 kinds of triangles and have 2 that are impossible to draw.
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Worksheet
Curated OER

Triangles

For Students 4th
In this triangles worksheet, 4th graders study the lengths that are stated for 3 triangles and describe each triangle by its sides. Students describe 3 additional triangles by their angles.
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Worksheet
Curated OER

Classify Triangles

For Students 4th - 7th
Here is a classifying triangles practice instructional activity in which learners sharpen their problem solving skills as they solve six story problems.
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Lesson Plan
Curated OER

Acute Triangles

For Teachers 4th - 8th
Learners study acute triangles. They measure angles using a protractor, then classify the triangles as either right, obtuse, or acute. Everyone creates a design for a Navajo rug using only acute triangles.
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Worksheet
Curated OER

Triangles and Congruence

For Students 8th - 10th
Can your class construct triangles and determine congruence? Find out with this well put together worksheet. THey construct triangles to given specifications and identify if they are congruent. There are 3 muti-step problems to solve.
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Worksheet
Mt. San Antonio Collage

Isosceles Triangles and Special Line Segments

For Students 9th - 12th Standards
Under which conditions can a triangle be classified as isosceles? High schoolers practice identifying isosceles triangles and special line segments, including angle bisectors, medians of triangles, and perpendicular bisectors of sides of...
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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
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Illustrative Mathematics

Right Triangles Inscribed in Circles I

For Teachers 9th - 10th Standards
One of the basic properties of inscribed angles gets a triangle proof treatment in a short but detailed exercise. Leading directions take the learner through identifying characteristics of a circle and how they relate to angles 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 plan 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
Willow Tree

Angle Sum Property of Triangles

For Students 8th - 11th Standards
All triangles have some things in common. Using these properties of triangles, learners find missing angle measures. Scholars use the Angle Sum Property and properties of special triangles throughout the lesson.
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Assessment
Bowland

Rods and Triangles

For Teachers 6th - 9th
Scholars explore triangles with rods of different lengths. Using rods of 2, 4, 6, 8, and 10 cm class members build as many different types of triangles as they can. They also describe properties of these triangles and determine...
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Lesson Plan
EngageNY

Triangle Congruency Proofs (part 2)

For Teachers 9th - 10th Standards
Looking to challenge your students that have mastered basic triangle congruence proofs? A collection of proofs employ previously learned definitions, theorems, and properties. Pupils draw on their past experiences with proofs to...
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Assessment
Inside Mathematics

Circles in Triangles

For Teachers 9th - 12th Standards
Challenge the class with inscribed circles in triangles. The assessment task requests class members use their knowledge of circles and right triangles to prove two triangles are congruent. They go on to utilize their knowledge of...
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Assessment
Concord Consortium

Triangles: Angle Space

For Students 9th - 12th
Three angles in a triangle, three-dimensional space, it all seems connected somehow. Given several different triangles, pupils use the three angles of the triangle as coordinates to plot points in three-dimensional space. They explore...
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Handout
Mt. San Antonio Collage

Congruent Triangles Applications

For Students 9th - 12th Standards
Triangles are all about threes, and practicing proving postulates is a great way to get started. The first page of the worksheet provides a brief introduction of the different properties and postulates. The remaining pages contain...
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Worksheet
Curated OER

Find the Perimeter of Triangles

For Students 5th - 7th
For this perimeter worksheet, students calculate the perimeter of various different triangles. There are four problems to solve.
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Worksheet
Curated OER

Find the Side of the Triangle

For Students 9th - 10th
In this geometry worksheet, students investigate the missing side of  triangles given the other two sides. There are 5 questions with a solution key.
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Interactive
CK-12 Foundation

Special Triangle Ratios: Special Right Triangle Ratios

For Students 9th - 12th Standards
Go from one side length to any other side length with special right triangles. Individuals use the interactive to investigate the ratio of sides in 45-45 and 30-60 right triangles. Scholars make generalizations about the types of special...
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Lesson Plan
Curated OER

Triangles

For Teachers 6th - 10th
Pupils identify triangles in the real world and construct their own triangle using drinking straws. They explore abstract triangles and find additional geometric shapes such as trapezoids. Students discuss similar shapes and examine the...