Different types of fire lay that are appropriate and doable in snow
Can't remember what it's called but when you anchor (could be that!) in snow by burying a shovel or bag etc
melting snow, get an old pot and let it burn through to demonstrate that you need to be careful
Fire from Ice
Navigation different when the landscape is different and even different if you're cold and impatient
First aid, how cold affects the body
how cold affects our motor skills
get them cold and then get them to light a fire with matches or friction
Cold weather fire lighting
Build a wind break to shelter behind
if it's really cold how things turn brittle (could put stuff in the freezer to demonstrate, -10 deg here today, plenty of brittle things already
tracking, always good in snow, although can be hard on frozen ground
insulation, pack yourself with newspaper, leaves etc to increase insulation