As a child, I heard people play or sing songs with five or more verses—every verse the same dirge-like tempo, same key, same inflections… The intent of the songs deserved better. I wanted to arrange songs to reflect the message and engage the listener. Now I help my students create arrangements as well.
A very young student might play/sing only one note differently. It’s a start! Perhaps a vocal student has a two-verse song. She goes through the melody twice and ends. Ask her if she can think of a way to change the ending to have more impact. If she can’t think of anything, give an example and have her try it.
Play a repeated passage two ways: once identically and once with a change. Ask which version held his interest, or would keep an audience engaged.
Students singing together might start singing harmony by splitting to a third only on the final note. Starting simply might mean simply making them aware.