If it helps, I have a math ed degree and am not using CLE. I have used MCP, R&S and currently we are using Math Mammoth. If your son really likes being independent, Math Mammoth would be a good choice. All the explanations, examples, etc are built into the lesson. He could work mostly independently and come to you if he needs help. I have been going over the explanations with my dd, but she could probably do it herself. I just like to make sure she knows what to do before I let her loose to do the day's work. HTH!