Lesson Plan
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Altitudes and Orthocenters: Making Connections to the Nine-Point Circle

For Teachers 9th - 12th
Students practice various equations for constructing nine-point circles for triangles.
Lesson Plan
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Toe to Toe Geo

For Teachers 2nd - 6th
Students study triangles. For this triangle lesson plan, students compare and classify triangles while milling to music. Students will also trade triangles so they can match up with other similar triangles. Triangles are provided.
Lesson Plan
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Classifying Triangles Based On Properties of Angles

For Teachers 5th Standards
The interactive lesson plan featured here calls for the use of a Smartboard for sorting and classifying shapes. Then, pupils discuss the rules they followed for sorting their shapes, particularly focusing on the properties of angles....
Lesson Plan
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Sum of Angles on a Triangle

For Teachers 4th - 5th
Use this lesson for a basic review of angles. While the activities discussed are outlined, there are no materials provided to make implementation possible. When using this resource, it is necessary to create worksheets and other...
Interactive
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Cosines

For Students 9th - 12th
In this online math worksheet, learners practice finding the cosines given 10 different sets of data. When complete, students submit their answers and get instant feedback regarding their accuracy.
Interactive
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Law of Sines or Sine Rule

For Students 9th - 12th
In this online math worksheet, high schoolers construct triangles and squares by utilizing the sine rule. This excellent resource allows the students to check their answers, and to get "hints" should they run into difficulties. A...
Interactive
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Triangle Problems - Find the Height given the Area

For Students 9th - 12th
In this online math worksheet, learners find the height of 5 triangles given their area. This excellent resource allows the students to check their answers, and to get "hints" should they run into difficulties. A terrific teaching tool!
Worksheet
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Similar Polygons and Triangles Review

For Students 9th - 12th
In this similar polygons and triangles review activity, students solve 33 short answer problems. Students determine if two given polygons are similar. Students explain the type of similarity if they find two polygons to be similar.
Worksheet
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Easy Worksheet: Types of Triangles

For Students 9th - 12th
In this types of triangles worksheet, students solve 6 short answer problems. Students identify the type of triangle being described according to side length or angle measure.
Worksheet
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Family Activity: Triangles and Quadrilaterals

For Students 6th - 8th
In this triangles and quadrilaterals worksheet, students solve 7 short answer problems. Students find objects around the house that are constructed from triangles, parallelograms, trapezoids, squares, rectangles. Students sketch the...
Lesson Plan
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Area-Time to Get in Shape

For Teachers 9th - 10th
Students investigate the properties of triangles and parallelograms. In this geometry activity, students calculate the formula used to find the are of a triangle and other polygons. They create a visual model to represent their findings.
Worksheet
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Congruence in Triangles

For Students 9th - 10th
For this geometry worksheet, students identify and label triangles as being congruent or not. They use the SSS, ASA or SAS as their description. There are 18 questions with an answer key.
Lesson Plan
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Classifying Polygons

For Teachers 1st - 3rd
Students study polygons. In this math lesson, students play a game in which they learn the classification system for polygons. Students identify the properties of quadrilaterals.
Lesson Plan
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Obtuse Triangles

For Teachers 4th
Fourth graders explore obtuse triangles. In this geometry activity, 4th graders make obtuse triangles with paper and scissors. They determine how to find the center of their triangle.
Lesson Plan
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Isosceles Triangles

For Teachers K - 2nd
Pupils investigate triangles. In this shapes geometry lesson, students define and state the attributes for equilateral, scalene, and isosceles triangles. Pupils locate the prefix "tri" in a variety of words and make connections with the...
Lesson Plan
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Equilateral Triangles

For Teachers 4th - 5th
Students examine the attribute of equilateral triangles. In this equilateral triangle lesson, students examine a number of paper triangles to determine how they are classified. They determine how triangles are depicted in Navajo rugs.
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Angle-Side Relationships

For Teachers 9th - 12th
Students calculate the different sides and angles of a triangle. In this geometry lesson, students use triangular properties to define the relationship between two triangle. They identify missing angles using the interior angle theorem.
Lesson Plan
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Triangles in Architecture

For Teachers 10th - 12th
Students find triangles in the real world. In this geometry lesson plan, students analyze and identify properties of two and three-dimensional objects. They differentiate between similarity and congruence.
Lesson Plan
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How Far Am I Traveling

For Teachers 9th - 11th
Students solve for missing sides using the Pythagorean theorem. In this algebra instructional activity, students derive the six trigonometric values using the right triangle. They relate the Pythagorean theorem to the distance formula.
Worksheet
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Pythagorean Theorem

For Students 5th - 10th
In this Pythagorean theorem worksheet, students use the Pythagorean theorem to find the missing side of the triangles. Students complete 8 problems total.
Worksheet
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Counting Exercise

For Students Pre-K - 1st
In this counting worksheet, students count circles and triangles up to the number 5. Students complete 2 problems total on this worksheet.
Worksheet
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Perimeter and Area

For Students 6th
In this perimeter and area worksheet, 6th graders find the perimeter and area of different right triangles. Students complete 9 problems total.
Worksheet
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Triangles

For Students 3rd - 8th
In this triangles worksheet, students name the kind of triangle that is shown in the picture. Students name 3 different kinds of triangles.
Worksheet
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Value of Triangles

For Students 9th - 10th
In this geometry activity, students identify the missing sides and angles of triangles. They find the midsegment of each triangle. There are nine questions with an answer key.