When I take my son (5 years old) camping I always attach a bear bell to him so that I can hear him and easily locate him. He also carries a Fox40 whistle around his neck, which he knows to use whenever he is scared, lost, or can't see us. He wears bight clothes to enhance his visibility. At dusk I give him two glow sticks one I attach to him, the other so he can play with it. I do not think my son in an emergancy (lost, hurt, whatever) would have the mind to tie 150' of tape on a trail.

5 year olds might seem like little people but they do not have the ability to think problems thought. Untill a child is around 8 they should be supervised 100% when outside of there comfort area.