Math- Links Foundation « Square for Math » A lot of activities. An anuel calendar with math problems.
Pythagoras-math magazine. On the site you find pentominoeslinks.
Here are books about an area of mathematical recreations,
called geometric dissections.
In the world of geometric dissections Professor of Computer Sciences Greg Frederickson is a leading authority. He wrote three unique books on the subject which show old and modern achievements in this old and very popular puzzle theme. His latest, third book, Piano-Hinged Dissections: Time to Fold!, is about a specific kind of these puzzles with pieces mutually folded along connected edges, and joined by piano hinges each long as the respective edge of fold...