NRICH

NRich UK - https://nrich.maths.org

NRICH's was established by Toni Beardon and other University of Cambridge UK academics as one of the earliest educational internet developments. 

The resources cover primary through to secondary and are free and open to everyone.

NRICH is part of the Millennium Mathematics Project at the University of Cambridge. NRICH is made possible by donations and grants from organisations and individuals who share the commitment to giving all students access to a rich, imaginative mathematics education.

Specific useful links on mathematical thinking identified by authors contributing to this MESHGuide are:

But we recommend you explore this site fully if you are a mathematics teacher.