Illuminations - National Council of Teachers of Mathematics (NCTM)  

Additional Resources for All Grades
General Mathematics and Teaching Resources
"Math is an important part of life, and though it’s an historically dry subject, with a little applied passion it can change the way your students think about the world."  This site provides a variety of useful information and links to explore regarding teaching mathematics.
National Library of Virtual Manipulatives
Challenging activities for kids of all ages

Purplemath (Algebra)
Instructive site  with explanations for subjects from beginning Algebra to Advanced Algebra topics.

Figure This! Math Challenges for Families
"The home of the Figure This! Math Challenges for Families; parent-friendly, engaging learning activities for families to do together, based on high-quality, challenging, real-life mathematics. Sponsored in part by a grant from the U.S. Department of Education and the National Science Foundation."

Math Help
This site covers a number of mathematical topics, including numbers, decimals, exponents, statistics, fractions, geometry, ratio, proportion, percents and probability, integers, metric units, measurement, and beginning algebra. It mostly provides basic help for students in 4th through 8th grades.

Math.com
You can read about famous mathematicians, or look at the Wonders of Math, or use one of their calculators . . . But the Homework Help Search Engine makes this site totally great - You tell it what grade you are in, and what subject you need help with, and the search engine finds the best sites for you.

Professor Freedman's Math Help
"A mixture of sound, humor, color, animation and graphics with lots of help for the 'math anxious' student. Its aim is to give students a self-directed and entertaining way to learn basic math and algebra. The site includes tutorial lessons authored by students, math assignments, study skills tips, links to free tutors and learning style information -- all with really 'cool' animation and music." Teachers might use this site as a guide to produce their own learning website with student authors.

Coolmath4kids.com

An interactive "amusement park of math and more -- especially designed for FUN, FUN, FUN!" This site is for kids of all ages, including parents and teachers.

Games and Other Resources for Teachers and Students

• Mathworld -
• A Math Dictionary for Kids- animated, interactive math dictionary for kids which explains over 400 common mathematical terms in simple language. 
• Math Glossary Harcourt Multimedia Glossary by Grade level 
• English Spanish Math Dictionary- Dictionary that translates math words into English and Spanish
• Understanding Math - Guides and worksheets to support the Understanding Math Software
• Project Interactivate - interactive courseware for elementary and middle school mathematics explorations
• Dave's Math Tables- Math Reference Tables by Topic 

   Other Helpful Resources:

   Math Solutions Online - Marilyn Burns
   Marcy Cook
   Texas Instruments
   Casio
   AIMS Education Foundation