Talk to him about choosing words that get his meaning across to his audience.
This advice is so useful to me. I actually was an English teacher for seven years and worked on this issue with my writing students, but it never occurred to me to apply it to "real life." I see how I can discuss this issue with my son in a meaningful way without making him feel like I'm really saying, "You are smarter than your friends, so you need to talk down to them," which is the LAST message I would ever want to send!
