This site defines eleven theorems relating to parallel lines and similar and congruent triangles. Links to the theorems and relevant term descriptions are provided.

This site defines parallel lines, parallel lines cut by a transverse, and congruent triangles. It also contains links for related terms.

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...

Students can use the TI-84 Plus family with Cabri Jr. to prove triangle congruence with SSA.

Students can use Cabri Jr. to discover two properties of similar triangles: corresponding angles are congruent and corresponding sides are proportional.

In this lesson on congruent triangles, students explore how to use postulates to identify if triangles are congruent by SSS, SAS, ASA, and AAS.

Given two triangles, determine whether they are congruent and use that to find missing angle measures. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.

This learning tutorial describes the characteristics of similar figures and how to use scale factor and proportions to determine missing side lengths. The lesson includes PowerPoint presentations and videos demonstrating how to solve...

[Free Registration/Login Required] This flipchart is a look at angles in geometry. Drawing, labeling, measuring, special angles: (right, straight, acute, obtuse) and congruence.

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.

The Chinese character mark for Tan II (pronounced she-tow-bah) is the second of two lessons to introduce first grade students to geometry using tangrams. This lesson incorporates history, math, and language arts. In this lesson students...

Students, teachers, and parents alike will enjoy this challenging math site. It contains a clever brain teaser section plus creative problems related to algebra, geometry, measurement, numbers, statistics, and probability. A Spanish...