These sites are directly linked to the specific California State Standards that the class is covering. The following sites are extremely user friendly.
6th Grade Math textbook support http://www.classzone.com/books/math_cs1/index.cfm?state=CA
7th Grade Math Text support http://www.classzone.com/books/math_cs2/index.cfm?state=CA
8th Grade Math Textbook support. http://www.classzone.com/books/algebra_1_cs/index.cfm?state=CA