Graphmatica

This software allows you to graph any function, written not only as y = f(x) but also in other formats.

Download from this site: http://www8.pair.com/ksoft/

Graph Paper

Create and print graph paper in a choice of many different formats - including square, rectangular, triangular, hexagonal, polar, logarithmic, etc.

Download from this site: http://www.marquis-soft.com

Geometer's Sketchpad

This dynamic geometry software is great for secondary math students. They can investigate the sum of the measures of angles in a triangle or other polygon, perform geometric transformations, investigate formulas, etc. It is a great tool for secondary I to secondary IV. This shareware version has all the capabilities of the purchased version, but you cannot save or print your work.

Demo Version: http://www.keypress.com/sketchpad

OOG

This software is based on the tangram. Students use their mouse to place tangram pieces onto a puzzle outline. Great for grades 4 to 7. Nice reinforcement when puzzle is completed.

Download from this site: http://www.mcmprod.com