I like to use a ribbon box to review.  I have a box about the size of a tissue box that has a slit cut in the lid, like the slot in a piggy bank.  Inside is one very long ribbon.  It is made of 2"wide pink, blue, and white ribbon cut into various lengths and stitched together.  I start by slowly pulling the ribbon out of the box.  When pink shows the girls sing, when blue shows the boys sing, when white shows everyone sings.  Hope this makes sense.  Imagine a magician pulling his never-ending string of scarves out of his black magic hat.  Oh there's an idea.  If you were planning on using the magic water already, you could add the magic box of ribbon, and maybe some other things?  Like letting a child lead with a magic wand, or as someone else suggested letting the magic wand choose who sings the next line of the song.  You know that game where you turn three cups upside down on the table and put a ball under one, then move the cups all around until your volunteer has lost track of where it is and then they have to guess the location of the ball?  There is a object lesson about the Holy Ghost it uses three boxes and a mouse trap.  You bring a child up front.  Set the mouse trap and place it in one of the boxes and put a piece of candy or a toy in the other two boxes.  Blind fold the child and tell them you are now going to switch the boxes around.  Tell the blind folded child to go ahead and try and find the candy/toy.  Most kids wont try because they are afraid of getting the mouse trap instead.  Tell the child to ask a friend or their teacher to come up and help.  That person directs the child's hand to the candy/toy.  You then compare the voice of the friend or teacher to the Holy Ghost.  Maybe you could use this to introduce the "The Holy Ghost" song.