Learning goals: Teacher Facing Calculate angle measures using alternate interior, adjacent, vertical, and supplementary angles to solve problems. Justify (orally and in writing) that “alternate interior angles” made by a “transversal” connecting two parallel lines are congruent using properties of rigid motions. Full lesson plan (warm-up, activities, synthesis, cool-down prompt) from 8.1 Rigid Transformations and Congruence, Grade 8.