Texas Education Agency
Texas Gateway: Generalizing Geometric Properties of Ratios in Similar Figures
Students will investigate patterns to make conjectures about geometric relationships and apply the definition of similarity, in terms of a dilation, to identify similar figures and their proportional sides and congruent corresponding...
Varsity Tutors
Varsity Tutors: Hotmath: Practice Problems: Similarity and Proportion Exercises
Twenty-four problems cover the topic of similarity and proportion in various settings. They are given with each step to the solution cleverly revealed one at a time. You can work each step of the problem then click the "View Solution"...
University of Georgia
University of Georgia: An Elementary Application of Similar Triangles
Excellent review site on similar triangles. Includes diagrams and explanation of application.
CPALMS
Cpalms: Why Are Circles Similar?
[Free Registration/Login Required] A comprehensive lesson plan for teaching how to prove that all circles are similar by using three types of transformations.
CPALMS
Cpalms: All Circles Are Similar
[Free Registration/Login Required] A formative assessment where students are asked to demonstrate how to prove that two circles are similar. Includes downloadable worksheet and a rubric, as well as followup questions to clarify or deepen...
Cuemath
Cuemath: What Is Similarity?
This mini-lesson introduces the properties of similarity and its role in geometry.
Texas Instruments
Texas Instruments: Similar Figures
In this activity, students investigate the properties of similar triangles.
Texas Instruments
Texas Instruments: Similarity and Dilations
Students will discover properties of similar figures using the TI-89 and CABRI Geometry II to use dilations to dynamically manipulate figures.
Texas Instruments
Texas Instruments: Similar Figures Discovery Activity
Students can use Cabri Jr. to discover two properties of similar triangles: corresponding angles are congruent and corresponding sides are proportional.
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.
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...
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.
Mangahigh
Mangahigh: Shape: Corresponding Angles
Explain that corresponding angles are the result of parallel lines being crossed by another line.
Mangahigh
Mangahigh: Shape: Recognize Similar Shapes
Determine if objects are similar by looking at proportions and the shape.
Mangahigh
Mangahigh: Shape: Solve Problems With Similar Shapes
Test your knowledge of similar triangles and shapes.
CK-12 Foundation
Ck 12: Geometry: Sas Similarity
[Free Registration/Login may be required to access all resource tools.] Use the SAS Similarity Theorem to determine if triangles are similar.
Khan Academy
Khan Academy: Determine Similar Triangles: Sss
Given two triangles with some of their side measures, determine whether the triangles are similar or not. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Khan Academy
Khan Academy: Determine Similar Triangles: Aa
Given two triangles with some of their angle measures, determine whether the triangles are similar or not. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
CK-12 Foundation
Ck 12: Geometry: Similar Polygons and Scale Factors
[Free Registration/Login may be required to access all resource tools.] This concept teaches students what similar polygons are and how to use scale factors to solve for missing information in similar polygons.