Don't ever underestimate how much a simple handwritten note will mean to someone of any age.
I sent this letter to a high school senior friend who just got into the college of his choice. His mother told me that he loved getting it so much that he read it out loud to her. I've omitted identifying info for privacy.
I just wanted to write and tell you again how proud Dr. Johnny and I are of you in getting accepted to NAME OF COLLEGE. The thing is, we were already proud of you, regardless of whether NAME OF COLLEGE had the good sense to accept you or not. You've worked hard, you've tried a lot of interesting things, and you've been involved in the life of your school and your community. These will all equip you well for whatever lies ahead, and we can't wait to see what that will be!
And always remember–whenever you stumble, you certainly haven't failed. You've just learned how NOT to do something the next time. Playing it safe in life has far fewer mistakes, but far fewer adventures.