It’s been say that God doesn’t always call the equipped, but He will equip the called. One of the best things you can do for your leadership is help them become more equipped to do what God has called them to do. You’ll find that not only will these trainer leaders do a better job of leading and teaching, they’ll stick with it longer and you’ll be doing less recruiting (a Kids Minister’s favorite past time).
Maybe you plan now for a Spring Leadership Training event and then another “Back to School Leadership Development” in the fall. Do an informal survey to see what the perceived needs may be (understanding how kids learn, telling a Bible story, guiding behavior, new ministry ideas are just a few possible training ideas). Make it fun, make it exciting, make it worth their time… the best way to get a developed ministry team is to be responsible for developing them.