Five year olds?

Whistle
Bright Poncho
Water
Snack
cheapie LED flashlight....they will lose it!
If lost, teach them to hug a tree, cover up with poncho if needed and blow the whistle.

Don't try to teach them everything at once.

As far as knives, every kid is different. I got all my kids Victorinox MY FIRST SAK PLUS. They have a combo tool (bottle/can opener/flat screwdriver) a blade with a rounded tip and a saw. My kids love the saw. The first time out, after the safety briefing <img src="/images/graemlins/wink.gif" alt="" /> was cutting walking sticks and stripping the bark off of them. Good lesson in both saw and blade use.