My wife and I had a discussion about our education just yesterday. We grew up in the era when kids were told: "Get a licking in school, you will get another licking when you get home".
We certainly respected out teachers and worked hard to absorb whatever they were teaching us. The high school that I went to had a very good superintendent that hired the best teachers of any high school in the county.
I still think back to the advantage I had from learning all I could in school; I found later that I was ahead of other kids when I went on to college.
I even remember working math problems in my head when I was driving tractors in the field. It's just pitiful to observe young people working in stores today that can't do any math in their heads. I often catch mistakes by doing math in my head while they are ringing up a sale; then I have to show them that they are wrong.
Keep encouraging that young man; he may not thank you for it now, but he will someday.