Illustrative Mathematics
Illustrative Mathematics: 8.g Congruence of Alternate Interior Angles
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.
Khan Academy
Khan Academy: Finding Angle Measures Between Intersecting Lines
Practice finding angle measures between intersecting lines.
CK-12 Foundation
Ck 12: Geometry: Alternate Interior Angles Intermediate
[Free Registration/Login may be required to access all resource tools.] This concept introduces students to alternate interior angles and how to use them to determine whether or not lines are parallel.
University of Georgia
University of Georgia: Inter Math: Alternate Interior Angles
This site offers a brief description of alternate interior angles, followed by an explanatory diagram.
CK-12 Foundation
Ck 12: Geometry: Angles and Transversals Study Guide
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...
Math Open Reference
Math Open Reference: Alternate Interior Angles
Explore the triangle inequality theorem with this helpful reference tool. Provides a detailed definition and an interactive activity that enhances further explanation. Includes links to related topics.
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math Alternate Exterior Angles
Dr. Math at the Math Forum offers a way of remembering alternate exterior and alternate interior angles by looking at the words and realize what they say and apply it to the picture.
Sonoma State University
Sonoma State University: Parallel Lines and Similar and Congruent Triangles
This site defines parallel lines, parallel lines cut by a transverse, and congruent triangles. It also contains links for related terms.
Math Words
Math Words: Alternate Interior Angles
This site offers a definition for alternate interior angles with a labeled graph and links to other related words.