This Instructional Activity is a part of the Lesson 2, Unit 2, Grade 8. We are going to describe how to define a translation along a vector by the use of an overhead projector transparency. Let the plane be represented by a piece of paper on which the vector has been drawn. Let be an arbitrary point in the plane (i.e., the paper), as shown. Note that we are using a finite rectangle to represent the plane, which is infinite in all directions, and a finite segment to represent a line, which is infinite in both directions.