In this interactive from APT, use basic facts about complementary, supplementary, vertical, and adjacent angles to solve for missing angle measurements. In the accompanying classroom activity, students measure the angles of different straight-line designs that they create, looking for patterns and relationships. Students then work with the interactive. By the end of the lesson, students can identify the four different types of angles and use that knowledge to identify the measurement of an unknown angle. This resource is part of the Math at the Core: Middle School Collection.