Cantact your local police, scout group and or SAR group and ask for the "Hug a Tree" program to be presented to the kids, used to be called woodsproofing.
Designed for that exact and age group. You need to be VERY! simple. I dont even cover compass or navigation to this age group.
Talk about responsibility its ok if you get lost nobody will be mad with you.
Talk about basic shelter (Orange garbage bag with hole in it) , ground insulation with debris, get out of the wind. Leave sign for searchers. Its ok to talk to strangers when you are lost. Hammer home STOP! stay where you are.
Make up a basic kit and show them and their parents:
Small waist pack that goes on them and stays on them near wilderness settings.
Id tag with all info including medical
Whistle on a breakaway string (get the child to test it, most are not for kids lung capacity)
Snack that wont melt or is too yummy

couple chemical handwarmers
role of surveyors tape, tie long strips to branches in the area they are lost
small toy
picture of family, laminated
Chemical light stick
Couple of kids bandaids
small easy to use LED light
2 orange garbage bags (demonstrate its use)
The hug a tree program covers all this and is the best tool out there for educating young kids.
Do not get too technical it will go in and out the ears. Get them involved with touching the gear and encourage questions. Demonstrait all gear so bring extras.
A child primer can be found here with some good info though based for a bit older children:
http://www.equipped.org/kidprimr.htm
Skam