I am drastically altering my Greek course for the upcoming year. I am glad you did not get involved with the last one. The book was, in my opinion, awful. I will recommend it as a reader in the future, but will never teach from it again.
That said, here is what I would recommend for your son. Start with duolingo. Greek comes out (so they say) in 9 days, on May 30. Here is the course offering page: https://www.duolingo.com/courses
Once this class launches, I will be setting up a Greek class via duolingo. Students will be able to interact with me and other students here.
As for class next year, I will be teaching Greek again, but I believe I am going to set the class up as a recorded class. In other words, I will be recording classes each week and will be uploading them for students to watch whenever they like. I will be teaching through (and re-writing) Henry Nunn’s New Testament Greek.
The last text was seriously complicated. I will be re-writing this one with the clearest explanations I can.
Since class will be recorded, any subscriber will have access and your son will be welcome to join and move at his own pace. I am hoping to have the first lessons up in August.
Let me know if you need more help!
Have a happy Saturday!