I suggest My Uncle Walter Waltzes With Bears.

Personally, although an ex-scout and cub myself I have never had experience singing to such groups as such groups. I have however sung songs to kids that age and found that they seem to like amusing songs, and/or songs with choruses that are easy to sing along with. Sea shanties often go over fairly well -- South Australia, or that one about Lord Nelson had a remedy to cure your mal de mer {sic} (which they seem to think is Mouldy Mare) They can roar along with the choruses.

However, we live in the age of Bevis and Butthead and suchlike so I agree that it is hard to get kids when amongst other kids to sing along. they are more prone to try when they are a few kids amongst adults. I find it is still easy to frighten them with ghost stories over the embers on the seashore in the dark so you might buy a few books of tradtional ghost stories.