Some of my favourite math resources come from the University of Waterloo Centre for Education in Mathematics and Computing – CEMC for short.
They run many math contests, which for a nominal fee you can enter your students in. One of my favourite math enrichment activities is to have my Grade 7 and 8 students work through previous GAUSS math tests individually, in pairs or groups. Students learn from each other when trying to solve these higher level math problems. Download Previous GAUSS math contests The previous years tests can be downloaded from their website in PDF format for free! I print these off and keep them in my Math Challenge Bin. You could also make the tests part of your math stations or centers program. I also upload these PDFs to my class website so students can practice at home if they wish.
Another math resource that CEMC creates is The Problem of the Week. Each week they send via email a math problem to your inbox that you can share with your class. The problems are sorted by curriculum strand and grade level. A new addition this year is the removal of grade levels from the problems. Problems are now classified by Level B-E. This makes differentiation so much easier. Level B is Grade 5/6 and Level C is Grade 7/8. You can differentiate math groupings or individual needs by creating math groups that align with the Problem of the Week levels. Problem of the Week
Math Frog for Grades 4-6: Grades 4-6 Online Math Games
Wired Math for Grades 7-10: Grades 7-10 Online Math Practice
I hope you enjoy using these resources as much as I do.