This resource from the Mathematics Assessment Project was found at OER Commons. https://www.oercommons.org/courses/finding-equations-of-parallel-and-perpendicular-lines/view. This lesson unit is intended to help teachers assess how well students are able to understand the relationship between the slopes of parallel and perpendicular lines and, in particular, to help identify students who find it difficult to: find, from their equations, lines that are parallel and perpendicular; and identify and use intercepts.

Exploring slope, including slopes of parallel and perpendicular linesMathematics Instructional Plans (MIPs) help teachers align instruction with the Mathematics Standards of Learning (SOL) by providing examples of how the knowledge, skills and processes found in the SOL and curriculum framework can be presented to students in the classroom.