Emathinstruction.com : Used for Algebra 1 and Algebra 2 Common Core. Free eTextbooks with corresponding videos.
https://www.khanacademy.org/ : Videos and instructional information for all levels of mathematics
www.brightstorm.com : Free SAT, ACT AP prep as well as video instruction in Algebra, Geometry, Trig/PreCalc, and Calculus
www.algebracomplete.com :This is a free online tutorial video series that includes over 30 full algebra lessons for students and teachers.
Google Classroom : Used in almost all of the math classrooms to post assignments, videos, and even hold class chats. A login is required for this website and information is shared by the math teacher.