Curated OER
Angles and Similarity
Students identify triangles as similar or congruent. In this geometry lesson, students drag triangles around on the navigator to see the effect of different angles on the shape of the triangle. They discuss angle similarity and angle...
Curated OER
Corresponding Parts of Similar Triangles
Here is a lesson that has learners take a look at corresponding parts of similar triangles, ratios of similarity, reductions and enlargements. They'll manipulate the scale factor (r) to observe the changes in similar triangles and then...
Other
Virtual Polyhedra: Polyhedra Names
An extensive look at the naming of various polyhedral shapes. Many hyperlinks for more information.
That Quiz
That Quiz: Practice Test: Triangles
Test your knowledge on the attributes of triangles. There are eleven levels that may be completed with or without a timer.
University of Georgia
University of Georgia: An Elementary Application of Similar Triangles
Excellent review site on similar triangles. Includes diagrams and explanation of application.
Oswego City School District
Regents Exam Prep Center: Similarity of Triangles
Discover the world of "similarity" in this test prep tutorial on similar triangles. Detailed explanation of concept with examples, challenging interactive practice, and a classroom activity that integrates math and science.
Texas Instruments
Texas Instruments: Constructing Triangles
This activity focuses on the various ways to construct the different types of triangles such as isosceles, equilateral, right, and right isosceles triangles. Students will begin by constructing triangles based on a minimal definition of...
Texas Instruments
Texas Instruments: Discovering the Quadrilateral Properties
This activity will use Cabri Jr. to allow students' the ability to discover all of the properties of each quadrilateral, rather than simply copying them out of a textbook.
Texas Instruments
Texas Instruments: Copying an Angle
Explore relationships (including congruence and similarity) among classes of two- and three-dimensional geometric objects, make and test conjectures about them, and solve problems involving them.
Science and Mathematics Initiative for Learning Enhancement (SMILE)
Smile: Similarity
This site contains a lesson plan for high school age learners. The objective is to discover the factor of proportionality in similar polygons and to relate this factor to the perimeters and areas of similar polygons.
Analyze Math
Analyze Math: Similar Triangle Problems
The geometry tutorial investigates similar triangles. The activity has several examples with detailed solutions.
Analyze Math
Analyze Math: Congruent Triangle Problems
The geometry tutorial investigates congruent triangles. The activity has several examples with detailed solutions.
Ministry of Education and Universities of the Region of Murcia (Spain)
Ministerio De Educacion Y Ciencia: Triangulos Semejantes
Learn how to recognize and construct similar triangles with these interactive activities.
Ministry of Education and Universities of the Region of Murcia (Spain)
Ministerio De Educacion Y Ciencia: Homotecia Y Semejanza
In Spanish. In this interactive activity you can understand and know how to apply direct and inverse homothety to simple shapes, apply Thale's theorem, construct similar polygons and work out their related measurements and know how to...
Math Open Reference
Math Open Reference: Similar Polygons and Triangles
A complete reference guide to similar triangles and polygons. It provides definitions and interactive activities that enhance further explanation.
Texas Instruments
Texas Instruments: Math Today Ballooning Inside the Box
In this activity Using the USATODAY infograph, "Ballooning inside the box", students will explore geometric relationships using similar triangles. Identifying triangles with two pairs of congruent angles to explore similarity properties...
Texas Instruments
Texas Instruments: Classifying Triangles by the Length of the Sides Using Cabri
This activity uses Cabri Jr. to classify triangles according to the length of their sides. [Requires Adobe Reader.]
Math Planet
Math Planet: Geometry: Congruent Triangles
Features a definition and a video lesson on congruent triangles with examples. [1:11]
Ministry of Education and Universities of the Region of Murcia (Spain)
Ministerio De Educacion Y Ciencia: Semenjaza
In Spanish. Interactive activities dealing with similar triangles and polygons.
Math Planet
Math Planet: Geometry: Polygons
A definition, examples, and a video lesson all help to explain polygons. [0:43]
Math Planet
Math Planet: Geometry: More About Triangles
Explores triangles and related vocabulary through examples and a video lesson.
McGraw Hill
Glencoe Mathematics: Online Study Tools: Similar Polygons
This site gives a short interactive quiz which allows students to self-assess their understanding of the concept of similar polygons.
Sophia Learning
Sophia: Using Corresponding Parts of Congruent Triangles
This lesson will demonstrate the use of CPCTC in triangle congruency proofs.
