I spend a lot of time out in the woods with my 3 and 6 year old daughters. I give them whistles and have taught them the "hug a tree" procedure if they get lost. In the past I also included a small water bottle, some hard candy, and an LED flashlight in small bags for them, but they'd always get sick of the bags and take them off. As they get older I'll try increasing the amount of gear they carry, but right now it's just the whistles.

-Blast

p.s. Sorry for the short answer, things are nuts here at work.