With my kids and grandkids, on their first shooting experience- 22 Hi Velocity HP, unopened can of soda. Blow up soda can in a fairly spectacular fashion. Clear rifle, have munchkin fetch can, we sit and talk for a minute.
Let them examine can. Explain that the expression "It's only a .22" was stupid. The destroyed can illustrates the first basic rule of firearm safety- never point gun at anything you do not wish to destroy.