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.
Worksheet
Curated OER

Angle Sum of Triangles and Quadrilaterals

For Students 9th - 12th
In this angle sum worksheet, students find missing angles of 20 triangles and quadrilaterals.  Students find the missing angle in each polygon by using the total degrees of each and given angle measures.
Lesson Plan
Mathematics Assessment Project

Identifying Similar Triangles

For Teachers 7th - 9th Standards
Math whizzes work with angle sums and exterior angles to figure out the measure of other angles. This particular publication provides comprehensive support in the form of an anticipatory activity, questions designed to prompt discussion,...
Organizer
Curated OER

Triangle Angle-Sum Theorem

For Students 5th - 8th
For this polygons worksheet, learners fill out a graphic organizer about the name of the polygon, the number of sides, the angle sums, and more. Students complete this for 5 polygons.
Lesson Plan
Hotchalk

Triangle Sum Theorem

For Teachers 8th - 10th Standards
Your visual geometry learners will appreciate triangle drawings as they model the triangle sum theorem and algebraically solve to find the missing interior angle in a triangle. Practice problems increase in complexity and vary in their...
Worksheet
Curated OER

Hands-On: Sums of Angle Measures

For Students 5th - 8th
In this angle measures worksheet, learners solve six word problems where they are given 6 different polygons, some of which are complex, and must determine angle measures in order to arrive at a solution.
Activity
Illustrative Mathematics

Find the Angle

For Teachers 7th - 10th Standards
This a fun problem for young geometers to play with while gaining important insight into deductive reasoning. Some will find the answers very quickly, others might take a less direct path, but all will use their knowledge of the sum of...
Worksheet
Curated OER

Geometry - Angles Overview

For Students 7th - 8th
Learners address 14 questions that include naming all pairs of opposite and supplementary angles for sets of intersecting lines and then, finding the measure of the unknown angle. They determine the measure of the angle that is...
Worksheet
Curated OER

To Be a Triangle Or Not To Be a Triangle?

For Students 10th
In this triangles worksheet, 10th graders solve and complete 10 different problems that include applying the Triangle Inequality Theorem. First, they use the illustrated triangles and the data table to test the theorem. Then, students...
Worksheet
Curated OER

Angles Activities

For Students 5th - 8th
A series of geometry worksheets have mathematicians constructing, dissecting, overlapping, and measuring as they analyze angles in various contexts. Learners use symmetry and reflections in a compass rose to write instructions on...
Lesson Plan
Illustrative Mathematics

Sum of Angles in a Polygon

For Teachers 8th - 12th Standards
How can learners use algebra to solve a geometry problem? Help learners create an equation that shows the relationship between the number of sides of a polygon and the sum of the interior angles. Students are asked to divide the...
Workbook
1
1
University of Utah

Geometry: Angles, Triangles, and Distance

For Students 8th Standards
The Pythagorean Theorem is a staple of middle school geometry. Scholars first investigate angle relationships, both in triangles and in parallel lines with a transversal, before proving and applying the Pythagorean Theorem.
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...
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...
Assessment9:45
Mathed Up!

Angles in Polygons

For Students 8th - 10th Standards
Show your class that finding angle measures is a regular calculation with a resource that provides 12 problems dealing with the measures of angles in regular polygons. Pupils use formulas for the sum of measures of angles in a polygon to...
Worksheet
Math Mammoth

Triangles 1

For Students 5th - 9th
In this triangles worksheet, students measure and calculate the measurements of eight triangles, their sums and classify the triangles as acute, obtuse or right.
Lesson Plan
Curated OER

Geometry Journal: Isosceles Triangles

For Teachers 10th - 12th
In this isosceles triangles worksheet, students justify and determine the symmetry of an isosceles triangle. They explore the bisector of rectangles. This three-page worksheet contains two problems. Answers are listed on page three.
Lesson Plan
National Security Agency

Classifying Triangles

For Teachers 4th - 8th Standards
Building on young mathematicians' prior knowledge of three-sided shapes, this lesson series explores the defining characteristics of different types of triangles. Starting with a shared reading of the children's book The Greedy...
Assessment6:43
Mathed Up!

Angles in Triangles and Quadrilaterals

For Students 8th - 10th Standards
This short video show viewers how to connect the sum of the angles in a triangle to other angle measurements. Pupils determine the missing measures for angles involved with triangles and quadrilaterals. Class members then must explain...
Worksheet
Curated OER

Countdown Challenge: Triangle Inequality Theorem

For Students 7th - 8th
In this triangle inequality worksheet, students test the Triangle Inequality Theorem. They measure the sides of given triangles, identify the type of triangle, and name angles in the triangle. The one-page worksheet contains 36 problems.
Lesson Plan
Curated OER

Study Buddies: Classifying Triangles

For Teachers 4th - 5th
In this math worksheet, students analyze an informative chart about the measurement and angles of equilateral, isosceles and scalene triangles. Students then answer 5 questions about classifying triangles.
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...
Activity
Illustrative Mathematics

Find the Missing Angle

For Teachers 7th - 9th Standards
This one activity requires young geometers to pull together information they are currently learning with things they have learned previously. Here they rely on understanding something about parallel lines, alternative interior angles,...
Worksheet
Curated OER

Properties and Attributes of Polygons

For Students 10th
In this geometry learning exercise, 10th graders determine if a polygon is convex or concave and apply the polygon Angle sum theorem and the polygon exterior angle sum theorem to determine the measures of interior and exterior angles of...

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