Triangle Resources

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Triangles
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2D and 3D Shape Sort: Factory
2D and 3D Shape Sort: Factory
Game
2D and 3D Shape Sort: Factory
Kids sort 2D and 3D shapes in this engaging geometry game.
Kindergarten
Math
Game
Identifying Shapes By Attributes
Identifying Shapes By Attributes
Game
Identifying Shapes By Attributes
Kids practice identifying simple shapes based on descriptions of their attributes.
1st grade
Math
Game
2D and 3D Shapes
2D and 3D Shapes
Worksheet
2D and 3D Shapes
Boost your child's understanding of geometry dimensions with this worksheet that challenges her to match 2D and 3D Shapes.
1st grade
Math
Worksheet
Fish Tangram Challenge
Fish Tangram Challenge
Game
Fish Tangram Challenge
Muggo needs to be fixed! Kids must use shapes to fill in a shark puzzle in this game.
Preschool
Math
Game
Counting 2
Counting 2
Guided Lesson
Counting 2
In this lesson, kindergarteners will be given the chance to focus on their counting skills with engaging exercises and guided instruction. Just as identifying the letters of the alphabet is a precurser to reading, so is counting to developing math fluency. Soon, your child will learn that the numbers they are counting have associated values, so the more practice they can get with counting the better.
Kindergarten
Math
Guided Lesson
2D and 3D Shape Sort: Car
2D and 3D Shape Sort: Car
Game
2D and 3D Shape Sort: Car
On the road again! Kids identify 2D and 3D shapes in this sorting game.
1st grade
Math
Game
Spider Web Shapes
Spider Web Shapes
Activity
Spider Web Shapes
Take the spookiness out of spiders with this web-making activity! Your child will practice talking about and creating shapes in this Halloween craft, and learn about spiders along the way.
Preschool
Math
Activity
Hexuzzle 2
Hexuzzle 2
Game
Hexuzzle 2
Develop a deeper understanding of how shapes fit together to form a hexagon.
1st grade
Math
Game
Shark Tangram Challenge
Shark Tangram Challenge
Game
Shark Tangram Challenge
Kids move tangrams into the correct positions to create a target shape.
Kindergarten
Math
Game
Geometry 2
Geometry 2
Guided Lesson
Geometry 2
Geometry in kindergarten involves the basics of measurement, shapes, and spatial reasoning. Designed and reviewed by teachers, this guided lesson gives kids an overview of these concepts with clear instruction and engaging exercises. Geometry practice in kindergarten can help bolster the skills needed for higher-level concepts in the later grades. You can give kids even more practice by downloading and printing the accompanying worksheets.
Kindergarten
Math
Guided Lesson
Know Your Shapes!
Know Your Shapes!
Lesson Plan
Know Your Shapes!
In this lesson, your students will become familiar with shapes by identifying them in real life. Your students will love identifying how many sides shapes have by drawing and counting them!
1st grade
Math
Lesson Plan
Geometry 3
Geometry 3
Guided Lesson
Geometry 3
First grade geometry covers basic shapes, as well as an introduction to 3D shapes. Our team of curriculum experts designed the following guided lesson, which provides an overview of first grade geometric concepts and gives kids lots of opportunities for practice. If your child needs more support in a different format, check out the suggested first grade geometry worksheets.
1st grade
Math
Guided Lesson
Geometry 4
Geometry 4
Guided Lesson
Geometry 4
This guided geometry lesson takes second graders on an exploration of 2D and 3D shapes. Kids will learn how to sort shapes, as well as partition them into halves, quarters and thirds. Tangrams are also featured within the exercise in order to give kids practical ways of practicing their new geometry skills. For more printable practice, try the geometry worksheets recommended by our curriculum advisors to accompany this lesson.
2nd grade
Math
Guided Lesson
Second Grade Fall Review Packet - Week 4
Second Grade Fall Review Packet - Week 4
Workbook
Second Grade Fall Review Packet - Week 4
This final installment of our Second Grade Fall Review Packet offers five more days of engaging activities that will prepare incoming second graders for a new year of learning.
2nd grade
Social studies
Workbook
Spot the Shapes
Spot the Shapes
Game
Spot the Shapes
Your child must look closely to find the shapes hidden in this picture!
1st grade
Math
Game
Basic Shapes
Basic Shapes
Worksheet
Basic Shapes
Bust out those crayons, it's time to test your knowledge of basic shapes! Have your first grader sort out these shapes by color.
1st grade
Math
Worksheet
Dive Into Data
Dive Into Data
Workbook
Dive Into Data
Math isn't just adding and subtracting—it's about making sense of numbers and information. Practice with calendars and different types of graphs to help your child dive into data!
1st grade
Math
Workbook
Shape Match
Shape Match
Worksheet
Shape Match
Help your child practice his skills in geometry with this printable worksheet, which asks him to name the different shapes.
1st grade
Math
Worksheet
Shapes From Every Angle
Shapes From Every Angle
Workbook
Shapes From Every Angle
Get in shape for geometry! From 2D to 3D, polygons to prisms, your child will soon be a shape master. After a review of important terms and concepts, he will practice identifying real world shapes.
1st grade
Math
Workbook
Triangle Time
Triangle Time
Lesson Plan
Triangle Time
Students will work hard to build shapes with straws in this hands-on lesson about the defining attributes of triangles. Use alone or with **Know Your Shapes.**
1st grade
Math
Lesson Plan
Shape Challenge: Find the Different Shapes!
Shape Challenge: Find the Different Shapes!
Worksheet
Shape Challenge: Find the Different Shapes!
A fun intro to geometry, this first grade math worksheet will help your child practice shape recognition and classification.
1st grade
Math
Worksheet
Shape Sort
Shape Sort
Lesson Plan
Shape Sort
Sorting takes on a new challenge for students in this activity which engages their critical thinking skills. As students determine defining attributes, they’ll figure out what makes a shape a shape!
1st grade
Math
Lesson Plan
All About Tangram Puzzles
All About Tangram Puzzles
Lesson Plan
All About Tangram Puzzles
Students will love composing shapes using tangrams in this hands-on lesson! Use this plan alone or as a support lesson plan for the **Tangrams: An Ancient Chinese Puzzle** lesson plan.
Kindergarten
Math
Lesson Plan
Tangrams: An Ancient Chinese Puzzle
Tangrams: An Ancient Chinese Puzzle
Lesson Plan
Tangrams: An Ancient Chinese Puzzle
How do you build spatial reasoning, critical thinking, and problem solving skills while doing something that is fun? With tangrams! In honor of Chinese New Year, this lesson introduces your students to the Chinese puzzle of tangrams.
Kindergarten
Math
Lesson Plan
Composing Shapes
Composing Shapes
Lesson Plan
Composing Shapes
Students will love composing and decomposing two-dimensional shapes using tangram puzzle pieces. Use this plan alone or to frontload key vocabulary and concepts taught in the lesson plan **Know Your Shapes.**
1st grade
Math
Lesson Plan

Triangle Resources

Triangles are one of the basic shapes used in geometry and a fundamental concept in trigonometry. They are defined as polygons with three edges and three angles. Students as young as preschool can be introduced to triangles, but keeping track of the different types can be difficult. For more definitions and equations before starting on the resources, see the bottom of the page.

Learn More About Triangles

A triangle is a polygon that contains three edges and three angles, with the three angles always adding up to 180 degrees. Changing the lengths of the edges or the degrees of the angles can make a completely different triangle!

Types of triangles
There are three special types of triangles that are determined by looking at how many sides or angles are equal.
  • Equilateral Triangle: This shape has three equal sides and three equal angles that are all 60 degrees
  • Isosceles Triangle: For this triangle, only two of the sides are equal. Similarly, only two of the angles are equal (e.g. two angles are 40 degrees, while the third is 100 degrees).
  • Scalene Triangle: This last triangle has no equal sides and no equal angles.
Types of angles
You can also the types of angles to identify a triangle:
  • Acute Triangle: All three angles are less than 90 degrees (e.g. 70 + 60 + 50 = 180 degrees)
  • Right Triangle: One of the angles is exactly 90 degrees (e.g. 90 + 60 + 30 = 180 degrees)
  • Obtuse Triangle: One of the angles is greater than 90 degrees (e.g. 110 + 40 + 30 = 180 degrees)
Common Equations
Using some basic geometric formulas, you can easily calculate the area and perimeter of a triangle.
  • Area: The area of a triangle can be found by taking half of the base and multiplying it by the height of the triangle (Area = ½ x base x height). If you need a refresher in multiplication, check out our multiplications page.
  • Perimeter: The perimeter of the triangle is the distance around the edge of the triangle. In order to get the perimeter, you add up the lengths of all three sides.
Now that you have a basic understanding of triangles, check out the resources on this page or move over to the geometry page to see how other shapes are used in math.