This Instructional Activity is a part of the Lesson 11, Unit 2, Grade 8. It is said that S is congruent to S' if there is a congruence so that Congruence(S) = S'. This leaves open the possibility that, although S is congruent to S', the figure S' may not be congruent to S'. Make sure students understand the question. Can you say for certain that if they begin by mapping figure 1 onto figure 2 they can also map figure 2 onto figure 1?