This lesson invites students to manipulate two rectangles using an applet to create similar figures and to study the effects on area ratios. Students verify proportionality and apply these concepts to structures in their world. This lesson is the first in a sequence of four lessons designed for students to understand ratio, proportion, scale factors, and similarity using perimeter and area of various simple shapes. The student learning guides are available in PDF, and discussion questions are included with the step-by-step activities. (author/sw/js)

Any career area that applies geometric principles will be able to use this resource to reinforce proportionality. The applet allows students to visualize the area while manipulating the sides of the figure. The application of this concept is most appropriate when creating scale models of structures or products. Students can understand area ratios in translating from scale models to actual construction. Graphic arts, journalism, and photography students will also use the principles of proportionality as they translate design to actual product.