This Instructional Activity is a part of the Lesson 11, Unit 2, Grade 8. Sequencing basic rigid motions has been practiced throughout the lessons of Topic B in this module because, in general, the sequence of (a finite number of) basic rigid motions is called a congruence. A geometric figure S is said to be congruent to another geometric figure S' if there is a sequence of rigid motions that maps S to S'.