In this lesson, students recall that in a transformation, a part of the first figure and its image in the second figure are called corresponding parts. This lesson re-introduces students to the concept that if two figures are congruent, then each pair of corresponding parts of the figures are also congruent. Students begin applying this concept in the next activity when they make and justify conjectures about a quadrilateral they form by transforming a triangle. Constructing a viable argument includes both writing conjectures and providing reasons to support that claim (MP3).

Technology isn't required for this lesson, but there are opportunities for students to choose to use appropriate technology to solve problems. We recommend making technology available.