Illustrative Mathematics
Find the Missing Angle
This one activity requires young geometers to pull together information they are currently learning with things they have learned previously. Here they rely on understanding something about parallel lines, alternative interior angles,...
Texas Instruments
Texas Instruments: Vertical, Adjacent, and Supplementary Angles With Cabri Jr.
Study Vertical, Adjacent, and Supplementary Angles with Cabri Jr. Page numbers come from Prentice Hall Geometry textbook.
Other
800score: Intersecting Angles
Read a description of intersecting lines and all about the different kinds of angles they form. Includes examples.