Page 3 keeps Randy's project pi (so it can be incorporated). I like Randy's approach as a first step for kids. Using this, especially in a class where they will all get slightly different perimeters for a four sided polygon, is a good way to start.
Still to do (previous entry clipped):
1) add label showing length of triangle segment to facilitate calculating perimeter
2) add label showing area
3) add Richo's graph tool to let the kids plot ratio of perimeter to diameter vs # of side, so they can see it converge
In the spirit of the group challenge I do not mind if anyone would like to take on any of the above items, help is always appreciated ;)
Stephen