Fraction Web Links
http://standards-e.nctm.org/1.0/normal/standards/standardsFS.html
This is a page of the newly proposed Principles and Standards Document of the National Council of Teachers of Mathematics. Clicking on "Standards" leads you to grade level standards for NUMBER AND OPERATION. Information on Integers and Fractions can be found at grade levels 3 – 5 and 6 – 8.
http://math.rice.edu/~lanius/Lessons/Series/infinite.htm
Visualizing an infinite sum of fractions.
http://www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Cardan.html
A biography of Cardan.