Just so they know, walking into the door to your room is where they turn on their creativity. This is the perfect poster to put above the stage, over the art door threshold, pointing to the pencil can or wherever you want them to begin imagining. They need to know.
This is what I teach my kindergartener's their first week in art. The cap is the hat that keeps the ink in. If we take it off, it dries up. If we snap it on and wait for the "click" sound, we will have a happy marker! If we have happy markers, we have happy artists!