I did this last year with my high school class using Rudiments of Music from Christian Light along with my own teaching. After numerous in-class training sessions, each student was given the responsibility to lead 3 songs during class singing time over the course of a month or two. I would always practice one-on-one with the student the day before to prevent embarrassment. This whole process was well received by the students. All students should know how to start and lead a song.