I took my Scouts to Hickory Run Stake Park in PA. We had just about 1:1 Scouts to Adults. They complained the whole time, because the temp when we got up was "6 Degrees". No one could start a fire; not the scouts, not the older scouts, not the adults. I finally had to get it going for them (hate to do that; it's better for them to try and fail and try and fail). But it was a bit brisk, eh?
I made double extra sure that _everyone_ including the adults had a buddy in their tent. We used dumb old Dome tents (I like them!), but I had a 0 degree Kelty bag my wife made sure we purchased when I got the position. Wore a long-sleeved T-shirt and undies. I 'wear' a t-shirt over/around my head instead of a cap. I get the warmth without the constriction.
In the morinig we wondered down to a 20 foot waterfall that was beginning to ice over, and they were having fun, begrudgingly.
When we got back, they couldn't stop braggin' about how they'd camped 'in 6 degree' weather.