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Worksheet
Mt. San Antonio Collage

Inequalities in a Triangle

For Students 9th - 12th Standards
Stuck with triangle proofs? Take a 180° and provide learners with a guided worksheet that tests their knowledge with triangle inequalities. The questions require different types of proofs that range in levels of difficulty. 
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Performance
Radford University

Building a Recreation Center

For Teachers 9th - 12th Standards
It's all about location, location, location. Small groups work to find the best spot for a rec center to serve three different communities. Learners construct the inscribed and circumscribed circles of a triangle to find the best place....
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Performance
Radford University

Finding a Location for Your Kitchen Island

For Teachers 9th - 12th Standards
Where is the best place to work? Small groups map out a kitchen on a coordinate plane and find the centers of the work triangle to find the best place to install an island. The teams use algebraic methods to locate the center by finding...
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Assessment
Concord Consortium

Short Pappus

For Students 9th - 12th Standards
It's all Greek to me. Scholars work a task that Greeks first formulated for an ancient math challenge. Provided with an angle and a point inside the angle, scholars develop conjectures about what is true about the shortest line segment...
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Assessment
Concord Consortium

Detective Stories

For Students 9th - 12th Standards
The truth will always come out. A short performance task has learners considering a witness statement given to a detective. They apply special line segments in triangles and Ceva's Theorem to prove that the witness is actually lying.
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Lesson Plan
Virginia Department of Education

How Many Triangles?

For Teachers 9th - 11th Standards
Something for young mathematicians to remember: the sum of any two sides must be greater than the third. Class members investigates the Triangle Inequality Theorem to find the relationship between the sides of a triangle. At the same...
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Lesson Plan
Mathematics Assessment Project

Deducting Relationships: Floodlight Shadows

For Teachers 9th - 12th Standards
Try to figure out what happens with shadows as a person moves between two light sources. A formative assessment lesson has individuals work on an assessment task based on similar triangles, then groups them based on their assessment...
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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
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Mathematics Assessment Project

College and Career Readiness Mathematics Test A2

For Students 9th - 12th
A six-page evaluation covers material included in algebra, geometry, and algebra II. Applied word problems are mixed in with short answer questions. It also provides questions on mathematical reasoning.
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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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Handout
Charleston School District

The Sum of Angles in a Triangle

For Students 8th Standards
An informative lesson contains a brief explanation of how the sum of the angles of a triangle is a line. The lesson continues with determining the missing angle in a triangle, or solving for a variable. Using the sum of the angles, the...
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Lesson Plan
EngageNY

Special Lines in Triangles (part 1)

For Students 9th - 10th Standards
Allow your pupils to become the mathematicians! Individuals explore the properties of a midsegment of a triangle through construction and measurement. Once they figure out the properties, learners use them to draw conclusions.
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Lesson Plan
1
1
Illustrative Mathematics

Placing a Fire Hydrant

For Teachers 9th - 10th Standards
Triangle centers and the segments that create them easily become an exercise in memorization, without the help of engaging applications like this lesson. Here the class investigates the measure of center that is equidistant to the three...
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Printables
K-5 Math Teaching Resources

Triangle Pack

For Teachers 4th - 6th Standards
With so many different types of triangles, it can be a challenge for young mathematicians to keep them all straight. Luckily this set of printable triangles is here to engage children in comparing and sorting triangles by their...
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App
iMagine Machine

The Land of Venn - Geometric Defense

For Students 2nd - 5th Standards
Young mathematicians use their geometry skills to save the Land of Venn in an engaging math game. A fun way to reinforce children's understanding of basic geometric figures and shapes.
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Lesson Plan
1
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Curated OER

Reflecting Reflections

For Teachers 7th - 9th Standards
A triangle rests in quadrant two, from which your class members must draw reflections, both over x=2 and x=-2. This focused exercise strengthens students' skills when it comes to reflection on the coordinate plane.
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Lesson Plan
Curated OER

Geometry Practice: G.G.28 #1: Congruent Triangles

For Teachers 9th - 12th
In this congruent triangles worksheet, students solve four multiple choice problems. Students determine which statement is the appropriate reasoning to say that two triangles are congruent.
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Lesson Plan
Curated OER

Mathematics Lesson for Grade 10

For Teachers 10th
There are four main topics in this bundle of lesson plans. They don't need to be taught sequentially. Each instructional activity has three parts: a starter, a main activity, and something to help consolidate and provide reflection on...
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Worksheet
Curated OER

Exploring Congruent Triangles

For Students 8th - 9th
In this congruent triangles worksheet, students solve 12 different equations related to writing a correspondence statement for triangles in the given diagrams. They complete each correspondence statement and write a congruence statement...
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Worksheet
Curated OER

Proofs

For Students 8th - 11th
In this geometric proof instructional activity, 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...
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Lesson Plan
Curated OER

Triangle Sum Theorem

For Teachers 9th - 12th Standards
Teach your class how to solve problems using the triangle sum theorem. In this geometry lesson, students identify the missing angles in a triangle using the sum theorem. They graph triangles on the TI and moves the sides around to create...
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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 instructional activity, 10th graders investigate the conditions necessary to prove two triangles congruent.  The instructional activity combines dry erase board activities and...
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Lesson Plan
Curated OER

Congruent Triangles

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

Hands On: Construct Triangles and Rectangles

For Students 4th - 7th
In this congruent triangles and rectangles worksheet, students solve 6 word problems where they identify whether triangles and rectangles are congruent, and construct triangles. Students must explain their reasoning and prove each answer.