One thing I included in my 6 year old's backpack is a lanyard I made for her out of red paracord (she loves the color) and heat shrink tubing (for a break away). On it I put a whistle and a small pelican LED flashlight. She loves it and insists on wearing it every time we go hiking. Her backpack contains most of the things listed already, although we keep an extra change of clothes in there as well. She likes to cross and play around creeks, so the chance of her getting soaked is pretty good.

Greg