Challenges / Problems / Puzzles
List of sites with problems hosted by the Math Forum.
Houghton Mifflin Math Center : - Math puzzles for grades 3-4, 5-6, and 7+.
Math Magic: Math challenges for all levels.
Geometry Forum Problem of the Week
Arithmetic Problems and Puzzles: - Problems and puzzles from the Math Forum.
Topology Games - The torus and Klein bottle are introduced through six simple games (a Java-capable browser is required). Simple to use (from upper elementary and up) introducing interesting and deep topic.
Sequence Puzzles - A compilation of sequence puzzle resources.