- Franklin Institute Online
Franklin Institute Online provides a hotlist of math websites on general math topics such as problem of the week sites, information on mathematicians, and geometry topics.
- Grades 3-8 Puzzles
This education related site provides many math puzzles along with hints and their solutions for grades 3-8.
- Highland Middle School
Developed by Highland Middle School, this site shows hundreds of problems that were used as Problems of the Day at this school.
- Internet based lessons
A web page that offers excellent internet based lessons and hints that lead to some interesting solutions to mathematical problems
MATHCOUNTS® is an enrichment and competition program that promotes middle school mathematics achievement throughout the U.S.
- MathWorld Interactive
A site developed by MathWorld Interactive that posts challenging problems for K-3 (ages 5-8), 4-6 (ages 9-11), 7-8 (ages 12-14) and 9-12 (ages 14+) and the solutions that are submitted by students across the country. MathWorld also provides many number and interactive puzzle pages.
- Elementary School Problems of the Week
An archive of weekly problems and sample solutions for elementary school published by NCTM.
- Middle School Problems of the Week
An archive of weekly problems and sample solutions for middle school published by NCTM.
- Non-routine problems
This site is dedicated to allowing teachers and students to practice non-routine problems in a fun way. The site includes sets of problems for grades 5 through 12, and they are quite challenging!
- Problem Solving
An entire website dedicated to problem solving. Contains many links such as "How to solve problems," "A short course in problem solving," "K4-K12 problem set," and more. An excellent resource for teachers, parents and students.
- Problem-solving strategies
Using the NCTM's Curriculum and Evaluation Standards for School Mathematics as a guide, this site outlines problem-solving strategies with examples. The site provides specific links showing examples of such problem-solving strategies as looking for a pattern, drawing a diagram, making an organized list, and so on.