Illuminations Internet-based lesson plans (from the National Council of Teachers of Mathematics in the U.S.)
Connect-ME - "a place where the community of elementary school math teachers . . . meet to share problems, resources and stories."
General Mathematics and Teaching Resources - a compilation of resources for math professionals and teachers, including various teaching styles, links to mathematics journals for inspiration, and an abundance of sites dedicated to making math instruction accessible, fun, and worthwhile.
Math-Drills.Com - over 6000 free math worksheets with answer keys.
The Math Worksheet Site - create an endless supply of printable math worksheets. The intuitive interface gives you the ability to easily customize each worksheet to target your student's specific needs. Every worksheet is created when you request it, so they are different every time.
Math Worksheets from The Lesson Corner - create online math worksheets including answer keys
SuperKids Math Worksheet Creator "Have you ever wondered where to find math drill worksheets? Make your own here at SuperKids for free! Simply select the type of problem, the maximum and minimum numbers to be used in the problems, then click on the button! A worksheet will be created to your specifications, ready to be printed for use."
Mega-Mathematics Complete lesson plans for teaching relevant, exciting, and creative mathematics. Topics; The Most Colourful Math of All, Games on Graphs, Untangling the Mathematics of Knots, Algorithms and Ice Cream for All, Machines That Eat Your Words, Welcome to the Hotel Infinity, A Usual Day at Unusual School. (Primary, Junior, Intermediate)
Math Word Problems for Children "The goal of this web site is to help grade school children improve their math problem-solving skills. The pages are sorted by topic and level of difficulty. Each ready-to-use worksheet has enough room for students to show their work. You can print and use these worksheets free of charge."
Math Goodies features interactive math lessons, homework help, worksheets, puzzles, message boards, and more.
Exploring Data Links by level to relevant statistics Standards; lesson plans for collecting, analyzing, and/or displaying data; sources of data sets (Mac formatted), general information, courses, and statistics software on the Web.
Global Grocery List is a long standing project that generates real, peer collected data for use in various subject areas for computation, analysis, and conclusion-building. (Junior/Intermediate)