Applets Relating Two Polygons

Two Polygons:
Numbers of sides can be varied between 3 and 20; Graphs of perimeters and areas can be displayed; Uses the signature of a shape: the ratio of the square of the SemiPerimeter to the Area Applet Based on and developed from an idea of Dan Meyer 

Two Rectangles:
Sizes of rectangles can be varied; Graphs of perimeters and areas can be displayed; Uses the signature of a shape: ratio of the square of the SemiPerimeter to the Area; Applet 
More or Less Grids

How few cells can you change from the original for each of the 8 parts of the table?
Which is the most challenging and what makes it challenging? What principles about perimeter and area did you encounter? Applet See More or Less and Bi–Quality Tables 