Provides monthly puzzles with the goal of creating an engaging learning environment.

Calculus problems with archive and solutions.

Monthly problems with archive and results.

Weekly math problem and archive from Professor Alberto L. Delgado.

Calculus based problems range from easy to difficult.

Weekly math problem, with solutions, archive, and leader board.

Monthly problems.

A monthly on-line competition hosted by researchers at IBM.

Weekly math problem with solutions and archive.

Problem archive and puzzle links.

Weekly math problem and archive from Professor Stan Wagon for first-year college students presented by the Math Forum.

Past archive and solutions. Receive help from a mentor.

Past problems and solutions, student Recognition.

A weekly interactive project for elementary school mathematics. Past problems, solutions, and student Recognition.

Past archive and solutions. Receive help from mentor.

Weekly math problems and solutions from Math Forum.

Projects from the Math Forum presenting weekly interactive math challenges to accumulate points for bronze, silver and gold prizes. Individual or class participation.

Devoted to original mathematical recreations with puzzles and links.

Designed to assist teachers and students in problem solving. Includes problem of the month.

Math problems and solutions from Math Central.

A weekly contest for all students from elementary to high school. Prizes awarded each month.

Twice-monthly problems with archive and solutions.

Posted by the Mathematics Department of Bilkent University.

Sponsored by Shepherd College.

Links to problems of the week sites organized by grade levels.

Weekly math challenge with past problem archives and solutions.

Challenging problem open to college & pre-college students, faculty, and staff. Site also contains archive of past problems and solutions.

The Little Math Puzzle has been a K-12 Internet activity since 1995 for grades 5-9. Currently the puzzles have ceased but the site maintains complete archives of past problems.