Advice, guidance, ideas.....

The head of our school positive behavior team approached me the other day looking for ideas for a school mural.  The idea is to start small with a just an handful of students working on it and then add to the mural each year.  The focus would be on belonging.  I thought maybe depicting a connection of hands in a circle for the beginning and then adding around it each year.  Also, I visualized hands reaching upwards unified to a common goal.  Maybe children of different ethnic backgrounds holding hands.  I need some ideas!!!!   Has anyone done something like this and have some great ideas they could share?  This would be painted on walls that are cinder block and the idea is that students would do the painting.  I'm thinking I could project an image on the wall with my document camera to transfer the drawing prior to painting.  I even considered throwing it out to students to generate ideas but wonder if that would really be too overwhelming.  I have awhile to come up with an idea but thought my fellow art teachers might have been where I am and have some wonderful experience as well as great ideas.   Please Share!!!!