I would introduce TRANSPOSITION by placing three simple melodies on the board, asking the class if they could name the tunes. [Twinkle, Twinkle - Jingle Bells - Joy to the World]. Then I would explain the concept of transposition, especially its importance for a singer. Further explanation included the ability to transpose by interval (time consuming and the long way) or by key [faster and more efficient].
Assignment-SHENANDOAH: The printed score and the transposition should look identical, line for line - adding lyrics and all markings. The practice of transposition is critical to the life of every musician.
Once completed, I would play their transposed SHENANDOAH for the class.