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

Students construct a line parallel to the base of a triangle and measure the angles formed. They use the construction to prove that the sum of the measures of the interior angles of a triangle is 180 degrees.

This investigation uses Cabri Jr. and a cleaver rotation of a triangle to "prove" that the angles in a triangle add up to 180. This could be used to reinforce triangles and paralled lines as well as introduce the concept of rotating an...

This file contains questions related to parallel lines cut by a transversal and the angles formed. The questions can be used to asses your students' understanding of this topic in geometry.

Students learn about parallel lines and pairs of angles. Definitions and examples are included.

At the end of this lesson, students will be able to identify and apply the properties of lines and angles and understand the concept of parallel, perpendicular, complementary and supplementary angles, vertical angles, and parallel lines...

Students are challenged to identify and measure angles created by parallel lines and a transversal as well as complementary and supplementary pairs.

[Free Registration/Login may be required to access all resource tools.] Identifying types of lines as parallel lines, perpendicular lines or intersecting lines.

In this practice activity, students calculate angles created when two parallel lines are intersected by a transversal. Students receive immediate feedback and have the opportunity to watch a video, get hints, or try questions repeatedly.

[Free Registration/Login may be required to access all resource tools.] Use alternate interior angles to determine angle congruency and the presence of parallel lines.

[Free Registration/Login may be required to access all resource tools.] Use alternate exterior angles to determine congruency and the presence of parallel lines.

This study guide on lines and angles covers key terminology; line notation; parallel, perpendicular, and skew lines; and postulates and theorems about lines. It is available for download with free registration.

Eighth graders are presented with a labeled drawing of two parallel lines intersected by a transversal line. They are asked to discuss congruency of angles when the picture is rotated about a point on the transversal. Aligns with 8.G.A.5.

[Free Registration/Login Required] This flipchart defines parallel lines and planes. It defines a transversal, the concept of alternate angles, and vertical angles.

[Free Registration/Login Required] This flipchart regards parallel lines and relationship of angles created by a transversal. Includes lesson on vocabulary, Jeopardy-style game, and quiz.

Explains the basic concept of lines and angles with step-by-step instructions and methods for solving specific problems on your own relating to this topic.

Consider two parallel lines that are intersected by a transversal, and when it crosses the two others, many different angle pairs are formed. See the special properties of the angle pairs in this interactive.

[Free Registration/Login may be required to access all resource tools.] Use same side interior angles to determine supplementary angles and the presence of parallel lines.

[Free Registration/Login Required] Explore the relationships between parallel lines and the rules of angle measurements.

[Free Registration/Login Required] This flipchart gives information and examples of the relationships of angles when parallel lines are cut by a transversal.

This study guide on angles and transversals covers key terms, angle types formed by transversals, postulates and theorems about transversals, and how to prove if lines are parallel or perpendicular. It is available for download with free...

[Free Registration/Login may be required to access all resource tools.] This concept introduces students to same side interior angles and how to use them to determine whether or not lines are parallel.

Students explore the relationships of angles formed when two parallel or non-parallel lines are cut by a transversal. This activity investigates the terms: Transversal, corresponding angles, alternate interior angles, alternate exterior...

[Free Registration/Login may be required to access all resource tools.] This concept introduces students to alternate exterior angles and how to use them to determine whether or not lines are parallel.