I think that this requirement requires some serious re-work.  As parents, we trust that our center's will staff our chilren's school with appropriate individuals (who have been fully vetted).  I have observed first-hand the 16 and 17 year old helpers do amazing things with their classes and how the children respond to them.  The 16 and 17 year olds, I have seen, have flourished.  Please actually have observers come and watch some of these amazing young people in action.