Put a rainbow on the board either with paper or drawn on with colored chalk. Make signs or write different ways to sing (Hum, sing and jig, whisper, piano only, sing) and put them on the rainbow. Print out the little leprechaun and tape him on a stick.
When you are reviewing your month's song, move the leprechaun across the rainbow. Have the children do/follow what the leprechaun points to.