Curated OER
Fish Tale
Here is a cute problem that requires visualizing two-dimensional shapes within a three-dimensional object, and using properties of triangles and the Pythagorean theorem to solve a real-world problem. There is a small mistake in this...
Primary Resources
Different Types of Triangles
Are there different types of triangles? Yes there are, and this presentation describes each by its properties or characteristics. Right, equilateral, isosceles, and scalene are all shown and defined. The presentation isn't particularly...
Curated OER
Classifying Triangles by the Length of the Sides Using Cabri Jr.
Learners follow detailed directions to create triangles on their graphing calculator. In this properties of triangles lesson, they will create triangles on their calculators using the Cabri Jr. application. They then identify three...
Curated OER
Simson Line
Stuednts identify triangles for the Simson Line. In this geometry instructional activity, students solve triangular problems using the properties of triangles.They differentiate between the height, congruency and similarity.
Curated OER
Building With Triangles
Students participate in a unit on triangles. Through the unit they explore different way to make basic shapes using triangles. They also examine the basic properties of triangles and the relationships among basic geometrical shapes in...
Government of Alberta
Learn Alberta: Math Interactives: Exploring Shape Classification
Investigate the properties of triangles, quadrilaterals, and regular polygons using this interactive Learn Alberta math resource. Students are able to practice classifying shapes based on their different properties. Be sure to follow the...
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...
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.
Texas Instruments
Texas Instruments: Real Life Real World Activity Carpentry
Carpenters use applications of geometry in their work, including the properties of right triangles and circles. This activity uses Cabri Jr. Geometry software to make measurements and solve problems based on carpentry situations....
Khan Academy
Khan Academy: Identify Triangles by Angles
Practice identifying triangles by their angles as acute, right, or obtuse. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Khan Academy
Khan Academy: Identify Triangles by Side Lengths
Practice identifying triangles by their side-lengths as equilateral, isosceles, or scalene. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Mathigon
Mathigon: Geometry: Angles and Polygons: Drawing Triangles
This lesson focuses on the Triangle Inequality, when the sum of the lengths of any two sides of a triangle is greater than the length of the third. When this happens, the three sides cannot form a triangle.
CK-12 Foundation
Ck 12: Geometry: Triangle Relationships Study Guide
[Free Registration/Login may be required to access all resource tools.] This study guide reviews terminology for triangles, triangle properties, different types of triangles, and interior and exterior angle theorems.
Geometry Help
Geometry Help: Triangles
Explains the basic concept of triangles with step-by-step instructions and methods for solving specific problems on your own relating to this topic.
E-learning for Kids
E Learning for Kids: Math: Russian Toy Store: Angles Ii
Students will play learning games to explore triangles, angles, and angle measurement.
Wolfram Research
Wolfram Math World: Similar Triangles
Find the necessary information to decide if triangles are similar at this MathWorld site.