Lesson Planet
Search educational resources
  • Sign In Try It Free
  • AI Teacher Tools
    • Discover Resources Search reviewed educational resources by keyword, subject, grade, type, and more
    • Curriculum Manager (My Content) Manage saved and uploaded resources and folders To Access the Curriculum Manager Sign In or Join Now
    • Browse Resource Directory Browse educational resources by subject and topic
    • Curriculum Calendar Explore curriculum resources by date
    • Lesson Planning Articles Timely and inspiring teaching ideas that you can apply in your classroom
    • Our Story
    • Frequently Asked Questions
    • Testimonials
    • Contact Us
  • Pricing
  • School Access
    • Your school or district can sign up for Lesson Planet — with no cost to teachers
      Learn More
  • Sign In
  • Try It Free
  • Home
  • Teacher Resources

Browse by subject


Triangle

  • Pythagorean Theorem
  • Right Triangles
    • Pythagorean Theorem
    • Special Right Triangles
    • Trigonometric Ratios
  • Solving Triangles
    • Law of Cosines
    • Law of Sines
    • Law of Tangents
  • Angle Bisector
  • Angle Sum
  • Congruent Triangles
  • Perpendicular Bisector
  • Similar Triangles
    • Similar Right Triangles
  • Area of a Triangle
  • Equilateral Triangle
  • Isosceles Triangle
  • Trigonometric Ratio
  • Classifying Triangles

Show Related topics


  • Triangle Lesson Plans
  • Area Equation
  • Asymmetrical Shapes
  • Triangle Area Formula
  • Area of a Right Triangle

What Members Say


Amber J.
Lesson Planet has helped me take ideas I have and make them more streamlined, creative and higher level. It is great to see how other teachers present the same topic in a multitude of ways!
Amber J., Teacher
Fountain, CO

Triangle Teacher Resources

Hi, what do you want to do?

Create a lesson plan
Create a lesson plan
Generate resources with 80+ AI teacher tools
Generate resources with 80+ AI teacher tools
Search 200,000 instructional videos
Search 200,000 instructional videos
Find a teaching resource
Find a teaching resource
Find Triangle lesson plans and worksheets
Showing 6,692 resources
24 Items in Unit
Geometry Unit 4: Triangle Congruence
Lesson Planet Curated

Geometry Unit 4: Triangle Congruence

For Teachers 9th - 12th Standards
The Geometry Unit 4: Triangle Congruence unit module contains five lessons—each with a video, teacher reference, practice packets, solutions, and corrective assignments. To begin, scholars review the types of triangles, then investigate...
Get Free Access
30 Items in Unit
Geometry Unit 7: Right Triangles
Lesson Planet Curated

Geometry Unit 7: Right Triangles

For Students 9th - 12th Standards
Six lessons comprise the Geometry Unit 7: Right Triangles unit module. In the first lesson, pupils review the Pythagorean Theorem and determine how to use the converse to determine whether a triangle is right, obtuse, or acute. Next,...
Get Free Access
35 Items in Unit
Geometry Unit 3: Parallel and Perpendicular Lines
Lesson Planet Curated

Geometry Unit 3: Parallel and Perpendicular Lines

For Teachers 9th - 12th Standards
The Geometry Unit 3: Parallel and Perpendicular Lines Unit Module contains seven lessons, each with a video, teacher reference, practice packets and solutions, and corrective assignments. In the first lesson, pupils learn eight...
Get Free Access
20 Items in Unit
Geometry Unit 6: Similar Figures
Lesson Planet Curated

Geometry Unit 6: Similar Figures

For Teachers 9th - 12th Standards
Similar figures are the topic of Geometry Unit 6. Each of the four resources in the unit module contains a video, teacher reference, practice packets, solutions, and corrective assignments. In the first lesson, pupils learn the...
Get Free Access
29 Items in Unit
Geometry Unit 9: Area of Polygons
Lesson Planet Curated

Geometry Unit 9: Area of Polygons

For Teachers 9th - 12th Standards
Six lessons make up the Geometry Unit 9: Area of Polygons unit module. Pupils review the formulas for finding the area of parallelograms and triangles. They apply previous learning of trigonometric ratios and the Pythagorean Theorem to...
Get Free Access
12 Items in Unit
Common Core Algebra 2, Unit 9
Lesson Planet Curated

Common Core Algebra 2, Unit 9

For Teachers 9th - 12th Standards
Flip your classroom, or offer engaging visual aids to your lessons with a series of videos that explore the concept of trigonometry. After an introduction to the topic, high schoolers investigate reference triangles, unit circles, and...
Get Free Access
12 Items in Topic
Getting into Trig
Lesson Planet Curated

Getting into Trig

For Teachers 9th - 12th Standards
Starting with right triangles (SOH-CAH-TOA) and working up to the concept of radians, this collection introduces students to trigonometric ratios and supports them in learning to evaluate trigonometric functions.
Get Free Access
4 Items in Topic
Find the Area of Triangles, Quadrilaterals, and Polygons (6.G.A.1)
Lesson Planet Curated

Find the Area of Triangles, Quadrilaterals, and Polygons (6.G.A.1)

For Teachers 6th - 8th Standards
Before diving into the formulas for area, show where the formulas connect to the shape of the figure. The four videos look at different shapes and by decomposing them, they end up relating directly to their area formula.
Get Free Access
9 Items in Assessment Set
7th grade Math Remediation
Lesson Planet Curated

7th grade Math Remediation

For Students 7th Standards
Goal and Objectives for TEKS 7.5.C & 7.9.C: Students will solve mathematical and real-world problems involving similar shape and scale drawings; and determine the area of composite figures containing combinations of rectangles,...
Get Free Access
37 Items in Unit
Geometry Unit 5: Quadrilaterals and Polygons
Lesson Planet Curated

Geometry Unit 5: Quadrilaterals and Polygons

For Students 9th - 12th Standards
One's knowledge of angles should measure up to expectations. Scholars watch a video to learn about angles in polygons. They first see how to partition a polygon into triangles to find the sum of the interior angle measures. They then...
Get Free Access
38 Items in Assessment Set
Balanced Assessment: Exemplar High School Packet
Lesson Planet Curated

Balanced Assessment: Exemplar High School Packet

For Teachers 9th - 12th Standards
The Exemplar High School Balanced Packet is a collection of 19 assessment tasks designed to test scholars’ knowledge of Algebra 1 concepts. Learners create graphs that represent how things change over time, build functions to model...
Get Free Access
12 Items in Course
Flipped Math: Geometry
Lesson Planet Curated

Flipped Math: Geometry

For Students 9th - 12th Standards
Imagine taking a complete geometry course remotely! Eleven units make up the My Geometry course. Each unit follows the Flipped-Mastery cycle of learning, divided into two semesters. Pupils watch and take notes on a video that details the...
Get Free Access
12 Items in Topic
Math Antics Geometry Video Lessons
Lesson Planet Curated

Math Antics Geometry Video Lessons

For Teachers 4th - 8th Standards
The point of this collection of 12 videos is to introduce learners to three basic parts of geometry—points, lines, and planes. The presenter provides definitions, shows how to classify shapes, provides examples, and shows how to use...
Get Free Access
10 Items in Topic
Mathematics Vision Project: Interactive Applets
Lesson Planet Curated

Mathematics Vision Project: Interactive Applets

For Students 9th - 12th Standards
Ready, set, go! The Mathematics Vision Project provides a collection of 10 Interactive Applets that follow the progression of learning—to practice, develop, and solidify understanding. The interactives use engaging materials that include...
Get Free Access
6 Items in Assessment Set
Mathematics Assessment Project: Tests for College & Career Readiness - High School
Lesson Planet Curated

Mathematics Assessment Project: Tests for College & Career Readiness - High School

For Teachers 9th - 12th
A collection of six tests are designed to assess the College and Career Readiness of high school algebra I, algebra II, geometry, and statics and probability learners. Each assessment includes the test form and scoring and comes in 40,...
Get Free Access
8 Items in Unit
Utah Middle School Math Project: 7th Grade
Lesson Planet Curated

Utah Middle School Math Project: 7th Grade

For Teachers 7th Standards
The eight resources in this collection provide tweens with the tools and protocols for solving problems, enabling them to transition from acquiring basic knowledge to creatively applying it. The lessons in the workbook are Common Core...
Get Free Access
11 Items in Topic
Farm Printables Collection
Lesson Planet Curated

Farm Printables Collection

For Teachers Pre-K - 2nd
Teach your class about the farm with the ABCmouse.com! This collection includes coloring pages, a word search, and color-by-numbers pages. Access these and thousands of other resources for Preschool through 2nd grade at...
Get Free Access
3 Items in Topic
Grade 9-12, Claim 2 & 4: Problem Solving & Communication Reasoning Supports
Lesson Planet Curated

Grade 9-12, Claim 2 & 4: Problem Solving & Communication Reasoning Supports

For Teachers 9th - 12th Standards
Small but mighty, a collection of three resources features presentation slides that prepare high schoolers for the Smarter Balanced assessment. Claim 2 features problem solving questions drawn from all content areas. Claim 3 focuses on...
Get Free Access
10 Items in Unit
Utah Middle School Math Project: 8th Grade
Lesson Planet Curated

Utah Middle School Math Project: 8th Grade

For Students 8th Standards
Prepare eighth graders for high school math and science classes with a collection of 10 lessons that help tweens make the transition from acquiring basic knowledge to applying it in more complex situations. These Common Core-aligned...
Get Free Access
29 Items in Unit
Geometry Unit 1: Tools for Geometry
Lesson Planet Curated

Geometry Unit 1: Tools for Geometry

For Teachers 9th - 12th Standards
Six resources make up the first unit in the Flipped-Mastery series for geometry. In the first lesson, scholars learn how to identify and name points, lines, and planes. They work with four postulates, then practice the skills for naming...
Get Free Access
10 Items in Topic
Grade 8, Claim 1: Concepts and Procedures Item Slide Shows
Lesson Planet Curated

Grade 8, Claim 1: Concepts and Procedures Item Slide Shows

For Teachers 8th Standards
Ten resources make up a collection of student and teacher-friendly slides that prepare eighth graders for the Smarter Balance assessment. Learners review rational and irrational numbers, convert repeating decimals to fractions, as well...
Get Free Access
38 Items in Assessment Set
Balanced Assessment: Advanced High School Math Packet
Lesson Planet Curated

Balanced Assessment: Advanced High School Math Packet

For Teachers 11th - 12th Standards
Nineteen resources make up the Balanced Assessment: Advanced High School Math Packet designed to test learners' knowledge in Algebra II, Geometry, and Pre-Calculus classes. To demonstrate their understanding of concepts related to these...
Get Free Access
20 Items in Assessment Set
High School Balanced Packet 2 Assessment Tasks
Lesson Planet Curated

High School Balanced Packet 2 Assessment Tasks

For Students 9th - 12th Standards
Good assessments can be hard to find and difficult to formulate. Designed as a collection of mathematics assessment tasks, the 20 resources in this packet can also be used as lesson openers, a review, or extra practice. The open-ended...
Get Free Access
Interactive
Study Jams! Area of a Triangle Interactive
Scholastic

Study Jams! Area of a Triangle

For Students 4th - 6th Standards
Even though there is a wide variety of different triangles in the world, knowing a single equation allows us to find the area of each and every one of them. Follow along with this step-by-step presentation as Zoe clearly models how to...
Get Free Access See Review

Other popular searches

  • Classifying Triangles
  • Congruent Triangles
  • Similar Triangles
  • Area of a Triangle
  • Area of Triangles
  • Types of Triangles
  • Special Right Triangles
  • Triangles Types
  • Right Triangles Trigonometry
  • Pascal's Triangle
  • Greedy Triangle
  • Classify Triangles
  • ← Previous
  • 1
  • 2
  • 3
  • …
  • 42
  • Next →
Loading more results...

Suggest a category

Please update the form below to suggest a new category.

You are going to suggest a category in:

Triangle (Change)

If incorrect, please navigate to the appropriate directory location.

Close
© 1999-2026 Learning Explorer, Inc.
Teacher Lesson Plans, Worksheets and Resources

Sign up for the Lesson Planet Monthly Newsletter

Open Educational Resources (OER)

  • Health
  • Language Arts
  • Languages
  • Math
  • Physical Education
  • Science
  • Social Studies
  • Special Education
  • Visual and Performing Arts
View All Lesson Plans

Discover Resources

  • Our Review Process
  • How it Works
  • How to Search
  • Create a Collection

Manage Curriculum

  • Edit a Collection
  • Assign to Students
  • Manage My Content
Contact Us Site Map Privacy Policy Terms of Use