Ask A Teacher - the ultimate online destination for Ontario high school homework help. Polynomials a pain? Chemistry confusing? Spend some time on Ask a Teacher—it's easy, fun and free!
District School Board of Niagara Curriculum Services
EdSelect - includes many reference sites for students and teachers
Learning Resources Canadian content - information and links for teachers and students
Links To Leaning - linking you to web sites supporting the Ontario curriculum for high school students
Ontario Ministry of Education - curriculum documents are organized by grade and by subject