Khan Academy is a free website that requires you/your child to sign up. This site is more effective when you are more involved with it. You can pick a curriculum on which your child can work. It includes video lessons on each topic and skill quizzes. When questions are answered incorrectly, students can try again, “get help” via an explanation of the problem and videos showing other examples before continuing, or skip the problem and come back later. When quickly successful, students can test out of a unit when they show early mastery.