What a great idea!
I am a strong believer in rites of passage; our culture has lost that and it is too bad.
I would recommend creating a statement or liturgy that could be used to acknowledge the foundations the young people have gained in their early years, that they can now build on as they move to a new phase of life and continue to grow in "wisdom and understanding".
You may want to present a certificate, pin, or some other tangible item.
It would be most appropriate for this to happen as a part of the worship service so that the entire congregation has the opportunity to recognize and celebrate the students.
Jan Snell