For winter survival for 4th graders out skiing, boarding or
snow shoeing, we recommend at least-

Synthetic and wool clothes on, no cotton and include a warm hat.
Large heavy duty trash bag in pocket.
Plastic whistle around neck.

Since they are not allowed knives at school and the heavy snows
here preclude making a proper fire for most mortals, knife and matches are not included in school oriented survival trainings.

Other things we recommend-
mini flashlight
water and snack


You have to keep it simple for them, so they will remember
without a big list to refer to.