This Instructional Activity is a part of the Lesson 11, Unit 3, Grade 7. This is a continuation of the previous one. Students use their cost computations from the previous activity to find the cost of an enlarged version of the stained glass window, which is now scaled by a factor of 3. Students recognize that the lengths of the frame and seams will increase by a factor of 3, while the area of the glass will increase by a factor of 3^2. If students observe that the material for the seams and the frame has width and the scale factor would need to be applied to this measurement, ask them if they can make a simplifying assumption.