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Lesson Plan
Curated OER

Indirect Proof and Inequalities in one Triangle

For Teachers 10th
In this geometry worksheet, 10th graders complete an indirect proof and order the sides or angles of a triangle. Also, students determine if a triangle can have sides with the given lengths. The two page worksheet contains twelve...
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Lesson Plan
Curated OER

Triangle Inequality

For Teachers 4th - 6th
Students discover that the sum of the lengths of any two sides of a triangle must be greater than the third side. They are shown how a triangle is formed using three strips such as that the triangle is seen inside the strips.
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Lesson Plan
Curated OER

Art or Junk? Discovering the Triangle Inequality

For Teachers 6th
Middle schoolers study the triangle inequality. They will identify, compare, and analyze attributes of two and three-dimensional shapes. Then they develop vocabulary to describe the attributes. They also use manipulatives to analyze the...
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Lesson Plan
Curated OER

Solving Problems Using Triangle Inequality Theorem

For Teachers 6th
Sixth graders investigate triangles and the inequality theorem. They will collaborate in groups to determine the length of a longest side of a triangle. Then relate the size of the triangle to its angles using protractors, yard sticks,...
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Lesson Plan
Curated OER

Triangle Inequality Theorems Investigation

For Teachers 9th - 10th
Students estimate and measure triangles. In this geometry lesson, students identify the relationship between three sides and a triangle. They use the inequality theorem to decide if a triangle will be formed or not.
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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...
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Lesson Plan
Curated OER

Indirect Proof and Inequalities in One Triangle

For Teachers 10th
In this geometry worksheet, 10th graders order the sides and angles of a triangle and determine the range of the third side of a triangle given the lengths of two sides.  The one page worksheet contains sixteen questions. ...
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Lesson Plan
Curated OER

Toothpick Triangles

For Teachers 4th - 8th
Students draw a chart (included in the lesson) to use with their investigation. They review terminology of triangles and receive toothpicks to use in the lesson. Beginning with three toothpicks, students form a triangle. They complete...
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Lesson Plan
Curated OER

Inequalities and Triangles

For Teachers 9th - 10th
Learners prove and apply theorems of triangle inequality and hinge theorem. In this geometry lesson, students will discuss which triangle is bigger and why. They will use theorems, such as Exterior Angle Inequality or the Pythagorean...
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Lesson Plan
Curated OER

THE TRIANGLE INEQUALITY IN ANIMATION

For Teachers 9th - 12th
Students open up the script to generate the sketch. They examine the viewing of the animation of a triangle. Students incorporate writing skills across the curriculum within this instructional activity.
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Lesson Plan
Curated OER

Pasta Triangles - A Triangle Inequality Activity

For Teachers 6th - 8th
Students explore, examine and experiment with pasta sticks to discover the triangle inequality principle. They assess if any three lines or segments fit together to form a triangle. Each student also completes a Triangle Recording Chart...
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Lesson Plan
Curated OER

Napolean Triangle

For Teachers 9th - 11th
Students investigate the Napoleon triangle theory. In this polygon lesson, students  differentiate between the boundary points, interior and lattice point of a polygon. They apply concepts of equilateral triangles to solve...
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Lesson Plan
Curated OER

Worksheet 7: Slope and Tangents

For Teachers 12th - Higher Ed
Providing both review and practice problems, this worksheet prompts students to answer five questions having to do with slope, tangents lines, graphing, the Squeeze Theorem, differentiable functions and derivatives. This activity could...
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Lesson Plan
Curated OER

Drawing Straws

For Teachers 4th
Fourth graders examine the Triangle Inequality Theorem by investigating possible lengths of the sides of a triangle.
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Lesson Plan
Curated OER

Angle-Side Relationships

For Teachers 9th - 12th
Students calculate the different sides and angles of a triangle. In this geometry instructional activity, students use triangular properties to define the relationship between two triangle. They identify missing angles using the interior...
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Lesson Plan
Curated OER

Triangle Conjectures

For Teachers 10th
Tenth graders investigate the theorems of ASA, AAS, AAA and ASA. In this geometry lesson, 10th graders discuss the theorems of triangles and how it is used to solve for missing sides or angles. They review how two angles are formed by...
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Lesson Plan
Curated OER

Triangles Congruency Theorems

For Teachers 10th
Tenth graders investigate the theorems of ASA, AAS, AAA and ASA. In this geometry lesson plan, 10th graders discuss the theorems of triangles and how it is used to solve for missing sides or angles. They review how two angles are formed...
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Lesson Plan
Curated OER

Triangle Sum Theorem

For Teachers 10th
Tenth graders investigate the theorems of angles and lines to prove triagle sum theorem. In this geometry lesson, 10th graders discuss the theorems of triangles and how it is used to solve for missing sides or angles. They review how two...
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Lesson Plan
Curated OER

Which Triangles are Right

For Teachers 9th - 10th
Students apply properties of right triangles to solve problems. In this geometry lesson, students identify axioms and theorems using examples.
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Lesson Plan
Curated OER

Exploring the Hinge Theorem

For Teachers 9th - 10th
Students explore the application of Hinge Theorem. In this geometry lesson, students write inequalities, given two sides of a triangle. They solve problems with triangular inequalities using the proper theorem.
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Lesson Plan
Curated OER

Triangle Wars

For Teachers 5th - 8th
Students explore geometry by participating in a class card game. In this triangle lesson, students utilize playing cards with shapes on them which they group up and discard, similar to "Old Maid." Students complete a worksheet and answer...
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Lesson Plan
Key Curriculum Press

Triangle Inequalities

For Teachers 8th - 11th Standards
Properties about triangles are explored in this lesson. Geometers make conjectures about the length of a triangle's sides, the length of the angles in relation to the length of the sides, and the measure of the exterior angles of a...
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Lesson Plan
Curated OER

I'm So Sorry I Ate Chocolate

For Teachers 6th
Sixth graders investigate the magnitudes of the sides and angles of a triangle. They determine the proof of the Sine Rule before using it to solve triangles. They compare the Sine Rule to the Cosine Rule in this unit of lessons.
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Lesson Plan
EngageNY

Finding Systems of Inequalities That Describe Triangular and Rectangular Regions

For Students 9th - 12th Standards
How do you build a polygon from an inequality? An engaging instructional activity challenges pupils to do just that. Building from the previous instructional activity in this series, learners write systems of inequalities to model...