回复：question about piano lesson

To me, "i normally go beyond 30 minutes for each session" maybe mean he usually have more than 30 minutes-session like 45 minutes-session for the beginner. You can ask him how long your son will take from the beginning, and after you guys have agreement on time like 30 min or 45 min for each session..... you will just need to pay the rate for that. In my case, sometimes it takes longer than my session, (you can't stop in the middle of practice because time is up), but I don't need to pay extra.