well, first of all, goodluck! and they'll be great.
I'd start of by also saying a few words of encouragement, and some details of progress of your students and acheivements. Thank the parents like kateb said, and also give out certificates at the end. Don't panic, even when your students, the younger ones stop or can't remember their places like one of my friends. hehe, and be confident, that's about it, if you've got all of the arrangements ready, then don't worry much, it'll be good.