Lesson Plan
Curated OER

The Pythagorean Theorem and Classifying Triangles

For Teachers 9th - 12th Standards
Through the examination of the relationship between the lengths of the sides of a triangles students will learn the classification of triangles (acute, right, or obtuse).
Lesson Plan
Curated OER

Similarity and Dilations - Discover Properties of Similar Figures

For Teachers 9th - 12th Standards
Learners investigate properties of similar figures. In this properties of similar figures lesson, pupils construct similar figures using Cabri Jr. They dilate their figure to create a similar one, and discuss the relationships between...
Handout
El Paso Community College

Geometry Definitions

For Students 7th - 9th Standards
Geometry is full of shapes, figures, and corresponding things here and there. The guide shares all of the key pieces of geometric information in a nicely color-coded and labeled sheet. 
Worksheet
Curated OER

Triangles

For Students 10th
In this triangles worksheet, 10th graders solve and complete 22 different problems related to various types of triangles. First, they name the shortest and longest sides and the smallest and largest angles in each of triangles...
Worksheet
Curated OER

Right Triangles

For Students 10th
In this right triangles worksheet, 10th graders solve and complete 5 different types of problems. First, they solve each of the right triangles shown and express each answer correct to two decimal places. Then students find the...
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...
Lesson Plan
EngageNY

Similar Triangles in Circle-Secant (or Circle-Secant-Tangent) Diagrams

For Teachers 9th - 12th Standards
First angle measures, now segment lengths. High schoolers first measure segments formed by secants that intersect interior to a circle, secants that intersect exterior to a circle, and a secant and a tangent that intersect exterior to a...
Lesson Plan
EngageNY

Dilations as Transformations of the Plane

For Teachers 9th - 10th Standards
Compare and contrast the four types of transformations through constructions! Individuals are expected to construct the each of the different transformations. Although meant for a review, these examples are excellent for initial...
Worksheet
Curated OER

Constructions and Angles

For Students 6th - 10th
In this triangle constructing and classifying worksheet, students read through a tutorial on triangles and angles. Then, students complete 17 exercises in which they answer questions about angles and triangles. By clicking on the "Check"...
Worksheet
Curated OER

Angles

For Students 5th - 8th
In this angles worksheet, students answer multiple choice questions about different types of angles and measurements of angles. Students complete 6 questions total.
Assessment
Concord Consortium

Triangles: Angle Space

For Students 9th - 12th
Three angles in a triangle, three-dimensional space, it all seems connected somehow. Given several different triangles, pupils use the three angles of the triangle as coordinates to plot points in three-dimensional space. They explore...
Lesson Plan
Virginia Department of Education

Exploring Quadrilaterals

For Teachers 6th
Sort this resource into the Use pile. Scholars investigate attributes of quadrilaterals and then use the results to sort and classify the shapes labeling each figure with their properties to justify the classifications.
Interactive
Shodor Education Foundation

Squaring the Triangle

For Students 8th - 12th Standards
Teach budding mathematicians how to square a triangle with an interactive that shows a graphical proof of the Pythagorean Theorem. Pupils alter the lengths of the legs using sliders. Using the inputted lengths, the applet displays the...
Lesson Plan
Curated OER

Triangles

For Teachers 6th - 10th
Students identify triangles in the real world and construct their own triangle using drinking straws. They explore abstract triangles and find additional geometric shapes such as trapezoids. Students discuss similar shapes and examine...
Lesson Plan
Curated OER

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
Curated OER

The Truth About Triangles And Proofs

For Teachers 9th - 12th
High schoolers engage in a lesson that is about the classification of triangles and the mathematical proofs involved in working with them. They work on a variety of problems that are created by the teacher with the focus upon the...
Lesson Plan
Curated OER

Midsegments of a Triangle

For Teachers 9th - 12th Standards
Students analyze midsegments of triangles in this lesson. They use Cabri Jr. software to observe the relationships between interior angles and midsegments of triangles. Specific instructions for creating this lesson in Cabri Jr. are...
Lesson Plan
Curated OER

Midsegments of Quadrilaterals

For Teachers 9th - 12th Standards
High schoolers explore the concept of quadrilaterals as they find the midsegments of quadrilaterals using Cabri Jr. on a graphing calculator. They find midpoints, slopes, angles, and distances of lines and angles.
Lesson Plan
Curated OER

Special Right Triangles

For Teachers 9th - 12th Standards
Using the Pythagorean Theorem to solve for missing angles, students evaluate right triangles and their properties.
Unit Plan
Mathematics Vision Project

Module 6: Congruence, Construction, and Proof

For Teachers 8th - 10th Standards
Trace the links between a variety of math concepts in this far-reaching unit. Ideas that seem very different on the outset (like the distance formula and rigid transformations) come together in very natural and logical ways. This...
App
Krzysztof Haft-Szatynski

Move the Turtle

For Students 1st - 9th
Turtles are not known to be speedy movers, but have you ever tried to get them to move in a specific direction? How about getting them to move in a perfect circle? With this app, young computer programmers have to be on their toes to...
Worksheet
Curated OER

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.
Lesson Plan
Curated OER

Identify triangles

For Teachers 9th - 10th
Students explore triangles. In this geometry lesson plan, students will create note cards with pictorial depictions of right, acute,obtuse, scalene, isosceles, equilateral and equiangular triangles. Students will verbally describe each...
Lesson Plan
Curated OER

Types of Triangles

For Teachers 5th
Fifth graders explore the required functions of the Geometer's Sketchpad. Using the computer software, they construct similar triangles and identify them by angles and sides. Students classify triangles. Afterward, they complete problems...