This Instructional Activity is a part of the Lesson 13, Unit 4, Grade 7. Given three drawings that are scale drawings of each other and two scale factors, students compute the other related scale factor. Students compare two drawings and determine the scale factor of one drawing to the second drawing and also decide whether one drawing is an enlargement of the original drawing or a reduction. A scale drawing is a reduction of the original drawing when the lengths of the scale drawing are smaller than the lengths in the original drawing.