Savvas Learning
Colorful Triangles
Learners examine a figure made up of different types of triangles and then determine whether each triangle is right, acute, or obtuse. Next, they color each type of triangle a different color. Finally, pupils answer three fill in the...
Texas Instruments
Identifying a Triangle by its Sides and Angles
Identify triangles by their angle measures and side lengths by looking at and measuring angle measures and side lengths. Use Cabri Jr. to construct various triangles, then manipulate the construction to create the 6 types of triangles,...
Curated OER
Types of Triangles
Young math whizzes solve four problems in which a triangle with labeled angle measurements is analyzed. They mark if each triangle is acute, right, or obtuse.
Curated OER
Right Triangles
Learners classify triangles and make connections regarding angle measurements and attributes of acute, right, and obtuse triangles. They listen to teacher define and explain triangles. Everyone imagines a place where a broken wing for a...
Beacon Learning Center
Beacon Learning Center: Triangles Side by Side
This comprehensive web lesson describes how to classify triangles by their angle and side measurements. It provides real-world examples and exercises for students to practice the skill.
Oswego City School District
Regents Exam Prep Center: Angles and Triangles
On this site a viewer can learn about the different types of triangles, and categorized by either angles or sides. Tutorials are also included for interior and exterior angles of triangles. A teacher resource page includes a lesson plan...
Oswego City School District
Regents Exam Prep Center: Geometry Vocabulary Resources
A list of geometry definitions and a matching activity.
Mathigon
Mathigon: Geometry: Triangles and Trigonometry: Properties of Triangles
This lesson focuses on the properties of triangles, a closed shape that has three sides, three vertices, and and three internal angles. There are different types of triangles such as a right triangle, obtuse, and acute based on the...
Cuemath
Cuemath: Acute Triangle
Explore the world of acute triangles in this mini-lesson. Explores its properties, how to create it, and other interesting facts related to acute triangles.
Government of Alberta
Learn alberta.ca: Mathematics Glossary: Acute Triangle
Get a visual and animated definition of what an acute triangle is, as well as examples of acute angles in the real world. [Requires Java.]
AAA Math
Aaa Math: Types of Triangles Based on Angles
Students can practice classifying triangles based on angle measurements through a series of self-check exercises and timed learning games.
Rice University
Rice University: Geometry Online: Impossible Triangles
This site has an activity that displays several impossible triangles. The rules for triangles are also displayed. The student has to determine which rule has been violated for each impossible triangle.
Wolfram Research
Wolfram Math World: Acute Triangle
This MathWorld site gives a short discussion on acute triangles with links to related terms and topics. The site offers a discussion on the least number of acute triangles to compose various polygons, and a discussion on the relationship...
Texas Instruments
Texas Instruments: Classifying a Triangles by Their Angle Measure Using Cabri Jr
This activity uses Cabri Jr to classify triangles according to their angle measure. [Requires Adobe Reader.]
The Math League
The Math League: Figures and Polygons
This site provides definitions of different types of polygons and figures.
Homeschool Math
Homeschool Math: Triangles
This lesson plan provides students with an opportunity to practice drawing and measuring triangles and angles. It also shows pictures and gives definitions of each type of angle and triangle.
McGraw Hill
Glencoe Mathematics: Online Study Tools: Triangles and Angles
This site gives a short interactive quiz which allows students to self-assess their understanding of the concept of triangles and angles.
CK-12 Foundation
Ck 12: Elem Math: Classifying Right Obtuse or Acute by Angle Measure
[Free Registration/Login may be required to access all resource tools.] Students watch a video and attempt practice problems on how to classify triangles based on angle measures.
CK-12 Foundation
Ck 12: Elem Math: Classifying Triangles Within Composite Figures
[Free Registration/Login may be required to access all resource tools.] In this learning module, students are presented with a composite figure and must identify the types of triangles within it. An accompanying video demonstrates a...
CK-12 Foundation
Ck 12: Geometry: Triangle Classification Grades 8 10
[Free Registration/Login may be required to access all resource tools.] Classify triangles by side lengths and angle measures.
CK-12 Foundation
Ck 12: Geometry: Triangle Classification Grade 7
[Free Registration/Login may be required to access all resource tools.] Classify triangles by side lengths and angle measures.
CK-12 Foundation
Ck 12: Geometry: Triangle Classification Grade 8
[Free Registration/Login may be required to access all resource tools.] Classifying triangles by using angle measures and side lengths.
CK-12 Foundation
Ck 12: Geometry: Triangle Classification Grades 9 10
[Free Registration/Login may be required to access all resource tools.] This concept teaches students how to classify triangles based on their angles and sides.
CK-12 Foundation
Ck 12: Elem Math: Classifying All Types of Triangles by Lengths of Sides
[Free Registration/Login may be required to access all resource tools.] Students watch a video overview and attempt practice problems on classifying triangles based on length of sides.