This applet features an interactive grid for forming rectangles. The student can form a rectangle and then examine the relationships among perimeter, area, and the dimensions of the rectangle as the rectangle dimensions are varied. Using options for set area, set perimeter, and line of constraint, students can see the results when one or more variables is held constant. The applet also allows users to trace changes when using a set option. Copyright 2005 Eisenhower National Clearinghouse