Almost anywhere I go, I carry my Swiss army knife. I really think I use it every day. Knives make great gifts for boys and dads alike. Knives are dangerous, and can get your son into a lot of trouble if they make it to school. Be sure your son knows about the rules and practices good knife safety. Our sons each got their first knife when they earned their “whittling chip” in cub scouts.
The right size knife is as long as the boy’s hand is wide. I don’t recommend “sheath knives” for boys under 17.