Life of Fred is pretty entertaining. Though you may need to read the stories to your son. Teaching Textbooks, my older daughter's favorite, has video tutoring

Life of Fred is pretty entertaining. Though you may need to read the stories to your son. Teaching Textbooks, my older daughter's favorite, has video tutoring. Singapore Math is good, too. There are programs you can look for that have lots of manipulatives. Don't recall the company names. Learning how to use an abacus was something the kids enjoyed and helped with ways of thinking about numbers quite a bit. You may find researching what home schoolers are doing for math programs helpful.