I've been doing this for a few years with one of our local primary schools... don't worry they'll not be short of stuff to say even if you are lol! Stuff to try on always works... helmets, caps etc... gear... belts, webbing... pick the smallest kid and load him up..! Stuff to show that would've appealed to them had they been that age during war time... shrapnel, tin toys (wot no wii !!!), wooden toys, "got any gum, Chum? etc etc... Take a wide range of stuff and you'll be fightin' the little monkeys off!! Watch out for knives n deacts though... sounds obvious but i had stuff tied on that i hadnt considered as being dangerous till the truck was surrounded in a schoolyard by little hands!!
One of my highlights last year was...
Whats that?
Its a typewriter
Cooooooool... wassit for?
You do get a feeling of 'passing on enthusiasm' which is nice.
You also get to make someones day/week/month
I did one last year where one little lad was so over excited at the prospect of seeing a real army truck the teacher said he'd been sick! He was stood at the back looking sheepish and green so i told him to 'sit in the drivers seat, put on that helmet on and guard the truck whilst i natter to the rest'... It was worth the lost day for the look of sheer delight on his face...