What do you think of me giving my son extra studies in the summer?
Is he having difficulties with certain class subjects?
Yes, he isn't very good at math.
It's great that you care so much about your son's education. Summer classes are a great way to help your son catch up on the subjects that he is weak in. If you don't give him extra studies, he will easily fall behind in school.
Are you sure it isn't a stupid idea? He might want to play video games with his friends.
No, it sounds like you are being a good parent. Your son can still play games, but keeping his mind working even during vacation can be helpful to him going into the next school year.