Other
Problems in the Points Contest of Ko Mal
Learn about the annual KoMal competition in mathematics, physics, and information technology, and challenge your ability to solve problems involving advanced algebra, logic, and other related topics through the tests provided at this site.
Other
Juegos, Acertijos, Y Recreaciones Matematicas
In Spanish. A variety of logic problems, including puzzles and word problems with links to the answers. An excellent site to engage Spanish speaking students.
Cut the Knot
Cut the Knot!: Interactive Mathematics: Geometry Articles, Theorems, Problems
Contains over five hundred Geometry articles, problems, puzzles, and games. Some sites relating to circles are provided within this list.
Other
Epsilones: Problemas Pi
Use logic or your knowledge of mathematics to solve this collection of math problems. Solutions are provided. [In Spanish]
Other
Mystery Master: Logic Puzzles
Find several logic puzzle ranging from "very easy" to "very challenging."
US Department of Education
Helping Your Child Learn Math: Math for the Fun of It
This compilation of math activities engages parents and children in the use of math whenever they are at home. Packed with concise, high interest activities, related illustrations, detailed "parent pointers," and easy to following...
Other
Foundation for Critical Thinking: Elemental Structure for Analytical Thinking
Dissect the eight elements identified which make up the human thought process. Everyone thinks and everyone follows this course to produce thoughts.
Ducksters
Ducksters: Kid's Games: Rules of Checkers
Kids learn the basic rules and strategy of the game of checkers on this site.