Several years ago I discovered a company called Time4Learning. What this company offers homeschoolers is amazing. They have curriculum available for preschool through eighth grade, which includes math, grammar, social studies, and science. All of the lessons are available online, and parents never have to download any software to their computer.
What I love about Time4Learning is that parents can use it as a main curriculum, or as a tutoring tool for the subjects their child is having trouble with. I had my daughter complete the math lessons during her sixth grade year, as she was having a bit of trouble understanding some of the concepts. The lessons are interactive, and often contain goofy characters that capture a child's attention. You won't have to beg your child to do their school work. He will want to do it!