Our version of Marden's Applet
How it works:
<param name=r value="0.95"> - The correlation goal.
<param name=nmin value="20"> - The minimum number of points which must be added to the plot
<param name=tol value="0.03"> - The tolerance for the correlation. The exercise will end when the student gets within plus or minus tol of r with at least nmin points.