Khan Academy
Khan Academy: Equation Practice With Vertical Angles
Given algebraic expressions that represent a pair of two vertical angles, form and solve an equation. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Cuemath
Cuemath: Perpendicuar
A comprehensive guide for learning all about perpendicular lines with definitions, how to draw them, solved examples, and practice questions
University of South Florida
Fcat: Reflection: Teacher Notes
Students use the coordinate plane to investigate how reflections affect geometric shapes. Can be used by the student, but is also a great lesson plan idea for teachers.