Worksheet
Curated OER

Exploring Congruent Triangles

For Students 8th - 9th
In this congruent triangles worksheet, learners 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...
Lesson Plan
Curated OER

You Can't Go Wrong with a Right Triangle 1

For Teachers 4th - 5th
Fourth and fifth graders study the Pythagorean Theorem and apply it to find the missing side of a right triangle.
Worksheet
Curated OER

Unit 5: Worksheet 3 - Similar Triangles

For Students 8th - 9th
In this similar triangles worksheet, students use proportions to solve for the missing sides of similar triangles. This two-page worksheet contains 16 multi-step problems.
Lesson Plan
Curated OER

Pascal's Triangle

For Teachers 7th - 11th
Learners explore the concept of Pascal's Triangle. In this Pascal's Triangle lesson, students use an applet called 'Coloring Multiples' to explore Pascal's Triangle. Learners develop patterns starting with various numbers in Pascal's...
Lesson Plan
Curated OER

A Special Relationship

For Teachers 6th - 8th
Students discover the relationships of the lengths of the sides of right triangles and right triangles using a series of drawings on dot paper. They investigate and solve problems of standard (customary and metric units) and non-standard...
Lesson Plan
Curated OER

Finding the Area and Perimeter of Polygons

For Teachers 7th
Seventh graders practice finding the area and perimeter of polygons. In this polygon area lesson, 7th graders brainstorm shapes and take a walk to locate shapes. Students record properties of shapes and use various shapes to make a...
Interactive
Curated OER

Angles in a Triangle

For Students 9th - 12th
In this online math worksheet, students calculate the angles in a triangle given their measurements. This excellent resource allows the students to check their answers, and to get "hints" should they run into difficulties. A terrific...
Lesson Plan
Curated OER

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....
Worksheet
K12 Reader

Classifying Triangles

For Students 2nd - 3rd Standards
Bring math and reading informational text together with a reading comprehension lesson. After kids read about isosceles, scalene, and equilateral triangles, they answer five comprehension questions to demonstrate how they can use context...
Assessment
Balanced Assessment

Triangle in Circle

For Students 6th - 8th
Even kindergartners can draw triangles in circles, but the assessment task requires a bit more geometric knowledge. Scholars investigate triangles that have a diameter of a circle as one of its sides. They must consider triangles that...
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...
Lesson Plan
Curated OER

Patterns in Pascal's Triangle

For Teachers 5th - 11th
Students examine the patterns in Pascal's Triangle. For this recognizing lesson, students view a model of Pascal's Triangle and describe the patterns of the multiples. Students identify the shapes that are made within Pascal's Triangle.
Lesson Plan
Curated OER

Reflections and Equilateral Triangles II

For Teachers 9th - 10th Standards
Given the lines of symmetry in an equilateral triangle, your learners find where the pre-image vertices are mapped onto the new image. They explore the properties of equilateral triangles, the impact of reflections, and the...
Lesson Plan
1
1
Illustrative Mathematics

Similar Triangles

For Teachers 9th - 11th Standards
Proving triangles are similar is often an exercise in applying one of the many theorems young geometers memorize, like the AA similarity criteria. But proving that the criteria themselves are valid from basic principles is a great...
Lesson Plan
EngageNY

Using Trigonometry to Find Side Lengths of an Acute Triangle

For Students 9th - 10th Standards
Not all triangles are right! Pupils learn to tackle non-right triangles using the Law of Sines and Law of Cosines. After using the two laws, they then apply them to word problems. 
Lesson Plan
EngageNY

Informal Proof of AA Criterion for Similarity

For Teachers 8th Standards
What does it take to show two triangles are similar? The 11th segment in a series of 16 introduces the AA Criterion for Similarity. A discussion provides an informal proof of the theorem. Exercises and problems require scholars to apply...
Interactive
CK-12 Foundation

Identifying Sets of Pythagorean Triples: Matching Problem

For Students 8th - 12th Standards
What sets of whole numbers make up the measures of side lengths in right triangles? Pupils use an interactive triangle to learn about Pythagorean triples. Individuals find missing values in triples and learn more about Pythagorean...
Activity
Education Development Center

Similar Triangles

For Students 8th - 10th Standards
Model geometric concepts through a hands-on approach. Learners apply similar triangle relationships to solve for an unknown side length. Before they find the solution, they describe the transformation to help identify corresponding sides.
Lesson Plan
West Contra Costa Unified School District

Law of Sines

For Teachers 10th - 12th Standards
One must obey the sine laws. A instructional activity introduces and derives the Law of Sines for non-right triangles. With examples that use the Law of Sines to determine unknown measures in triangles, the instructional...
Lesson Plan
Willow Tree

Interior Angles, Exterior Angles, and Diagonals of Polygons

For Students 8th - 11th Standards
How does the number of sides of a polygon affect the angle measures? Learners recognize a pattern in finding the total measure of interior and exterior angles and the number of diagonals. They use the patterns to calculate...
Unit Plan
Mathematics Vision Project

Circles: A Geometric Perspective

For Teachers 10th - 12th Standards
Circles are the foundation of many geometric concepts and extensions - a point that is thoroughly driven home in this extensive unit. Fundamental properties of circles are investigated (including sector area, angle measure, and...
Lesson Plan
EngageNY

Applications of the Pythagorean Theorem

For Students 8th Standards
Examine the application of the Pythagorean Theorem in problem-solving questions. Pupils apply the theorem to find lengths when given different scenarios. They finish the 17th installment in an 18-part series by applying the theorem...
Unit Plan
Arizona Department of Education

Area and Perimeter of Regular and Irregular Polygons

For Teachers 3rd - 6th Standards
Extend young mathematicians' understanding of area with a geometry lesson on trapezoids. Building on their prior knowledge of rectangles and triangles, students learn how to calculate the area of trapezoids and other...
Lesson Plan
EngageNY

Properties of Area

For Teachers 9th - 10th Standards
What properties does area possess? Solidify the area properties that pupils learned in previous years. Groups investigate the five properties using four problems, which then provide the basis for a class discussion.

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