That's a great kit for kids!!

I did a similar thing with my Cub Scouts a few years back when I was a den leader.

I went the route of using less gear on a small fanny pack in hopes they would be more likely to carry it more often.

Here is what we put together:

Fanny pack
Whistle w/ coiled wrist lanyard
Photon LED light
2 33 gallon orange plastic bags

First Aid Kit
First Aid Bag
4 - 3/4" 3M Active Bandage Strips
4 - 1" 3M Active Bandage Strips
3 - 3"x3" Gauze Pads
1 - Small Roll Adhesive Tape
1 - Small Soap in bag
2 - Latex Gloves in plastic bag
2 - Antibiotic Ointment
2 - Insect Sting Wipe
1 - Tweezers

The only thing I can advise for your kit is some tweezers and a plastic bag or sheet to use to sit on if the ground is wet - their poncho can cover the top of them. They might also use it to collect trash too.

Ken K.