Lesson Plan
Illustrative Mathematics

Lines of Symmetry for Triangles

For Teachers 3rd - 5th Standards
What can symmetry tell us about triangles? After looking at four examples, learners will come to realize that lines of symmetry are different for equilateral, isosceles, and scalene triangles. Use this guided practice activity as an...
Lesson Plan
Curated OER

Triangles

For Teachers 5th - 6th
For this math worksheet, learners answer 3 questions about an equilateral triangle. Students then answer 3 questions about isosceles triangles. Learners then calculate missing angles on isosceles triangles.
Worksheet
Curated OER

Classifying Triangles Using Sides

For Students 4th - 5th
In this geometry learning exercise, students answer 8 fill in the blank questions where they must examine 5 different complex geometric figures to classify triangles.
Handout
McGraw Hill

Triangles

For Students 4th - 7th Standards
After reviewing characteristics of seven types of triangles, young geometers discover how to find the missing angle of a triangle. Then, they practice identifying triangles, find missing angles, and find missing side lengths of...
Worksheet
Curated OER

Triangles

For Students 4th - 7th Standards
Why are there so many different types of triangles? Be that as it may, beginning geometers need to understand the differences between equilateral, isosceles, scalene, and right triangles, and they get a visual approach with this...
Worksheet
Curated OER

Classification of Triangle Measurement & Perimeter

For Students 10th
In this classification of triangles worksheet, 10th graders identify and complete 8 different problems that include determining the measurement and perimeter of various types of triangles. First, they color all right, acute, and obtuse...
Assessment
Concord Consortium

Isosceles Triangle Spaces

For Students 7th - 10th Standards
How many different types of triangles can your class name? A discovery lesson guides learners through an exploration of the different triangle types and the relationships between their angles and sides. Using coordinate geometry,...
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...
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...
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

Special Right Triangles and Right Triangle Trigonometry

For Teachers 9th - 11th Standards
Right triangles are so special! Use special right triangles to discover the trigonometric ratios. Pairs construct special right triangles and find the values of the ratios of the sides. In the process, they discover the ratios stay the...
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...
Instructional Video6:29
Corbett Maths

Pythagoras Rectangles and Isosceles Triangles

For Students 7th - 12th Standards
When does the Pythagorean Theorem come in handy? An intriguing video uses the Pythagorean Theorem to solve problems other than simply finding the length of a side of a right triangle. Pupils find the diagonal of a rectangle and the...
Lesson Plan
Curated OER

Isosceles Triangle Theorem

For Teachers 8th - 10th
In this geometry worksheet, students differentiate between regular triangles and isosceles triangles. They apply the converse theorem and the vertex angle. There are eleven questions with an answer key.
Lesson Plan
Curated OER

Study Buddies: Classifying Triangles

For Teachers 4th - 5th
In this math worksheet, pupils 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
Curated OER

Geometry of Triangles - Week 6

For Teachers 10th - 12th
In this triangle worksheet, students explore the characteristics of triangles. They find the area of a pentagon, lengths of the sides of a triangle and the area of a quadrilateral. This two-page worksheet contains seven problems.
Worksheet
Curated OER

Triangle Designs

For Students 4th - 6th
In this triangles worksheet, students draw different triangles and write how many sides and angles each one has. Students draw 4 kinds of triangles and have 2 that are impossible to draw.
Worksheet
Curated OER

Triangles

For Students 4th
For this triangles worksheet, 4th graders study the lengths that are stated for 3 triangles and describe each triangle by its sides. Students describe 3 additional triangles by their angles.
Worksheet
Curated OER

Classify Triangles

For Students 4th - 7th
Here is a classifying triangles practice worksheet in which learners sharpen their problem solving skills as they solve six story problems.
Worksheet
Curated OER

Triangles and Congruence

For Students 8th - 10th
Can your class construct triangles and determine congruence? Find out with this well put together worksheet. THey construct triangles to given specifications and identify if they are congruent. There are 3 muti-step problems to solve.
Worksheet
Mt. San Antonio Collage

Isosceles Triangles and Special Line Segments

For Students 9th - 12th Standards
Under which conditions can a triangle be classified as isosceles? High schoolers practice identifying isosceles triangles and special line segments, including angle bisectors, medians of triangles, and perpendicular bisectors of sides of...
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 instructional activity.
Assessment
Bowland

Rods and Triangles

For Teachers 6th - 9th
Scholars explore triangles with rods of different lengths. Using rods of 2, 4, 6, 8, and 10 cm class members build as many different types of triangles as they can. They also describe properties of these triangles and determine...