[L]ong or elaborate essay or discussion on a particular subject (OED)

Two columns I had in the PSMATYC Newsletter

Pulldown menus are not working under Internet Explorer because Microsoft is above compliance. In order to reach the sub-pages use the following links:

Lagrange Differential Calculus
An Interactive Demonstration of the Effect of the Length of a Sequence
A Different Stone
Reading Mathematics "Pencil in Hand"