Introduce Beavers to the principals of packing a rucksack and what to bring & Not bring for an overnight camp
Rucksack & lots of items you should bring and shouldn't bring(or pictures of items as an alternative)
Have an in out relay where they run up one at a time select an item from a pile of items in the middle or at the opposite end of the hall. Then in their lodge once all the items are collected sort into an in pile and an out pile. (alternatively you could have a in/out quiz with the items where one side of the room is in the other is out and they all run to their chosen answer)
Discuss their results focus on any contentious items, i.e. compass they may say in but for a beavers overnight camp each beaver doesn't need a compass but they do need a teddy!
Discuss the kit list, essential items for camps, discuss and demonstrate where different items should go in a ruck sack using the attached scout packing guide.