Wolfram Demonstrations Projecthttp://demonstrations.wolfram.com/An Open Resource of Interactive Mathematica VisualizationsCopyright 2009 Wolfram Demonstrations Project & ContributorsTiles around a Swimming Poolhttp://demonstrations.wolfram.com/TilesAroundASwimmingPool/]]>http://demonstrations.wolfram.com/TilesAroundASwimmingPool/Rectangles: Perimeter and Areahttp://demonstrations.wolfram.com/RectanglesPerimeterAndArea/]]>http://demonstrations.wolfram.com/RectanglesPerimeterAndArea/