Dave, I suggest you take a few minutes and show him how to properly hold a camera. Left hand under the lens for support with thumb and fingers on the lens and focusing as necessary. You might as well teach him good habits right from the beginning.
Probably the first time for me to look through the viewfinder of a MF camera, was when I was 6. My old man let me look through, at the time, his Nikomat FTn. First camera I actually used, was the Pentax H3v that I got for my 9th birthday in 1984. In 1987, I received my father's FTn. Had it for 10 years, before I sold it off and bought a Nikon FM to supplement my original FM2n. I did replace the FTn with a much cleaner body, about 8 months after selling the original body.
F4, F3P, F2A, F, FM2n, Nikomat FT2, FTn - John Laughlin Photography - nature photographer and NAS disease carrier
I don't remember how old I was when I first looked through the viewfinder of a camera. It was my dad's Argus 2 1/4 x 2 1/4 TLR sometime around the mid-1950s. I must have been pretty young since I got my own camera, a Kodak, fixed-focus TLR, when I was about eight. I remember that the ground glass image in the Argus seemed like magic to me. By the way, I still have both cameras.
I assume that Dave's son is too young to be perplexed that he can't see the picture immediately on the back of the camera but maybe not.
My Son, Sgt Dan USMC, certainly is the youngest, but his subject matter may be. He recently became a father for the first time. I gave him my old Pentax Spotmatic, 4 screw mount lenses, close-up tubes and all. The Pentax served me well for more years than he is old. I told him it was time to learn how to take real photo's. As is typical though, his wife took a greate interest in it than he did, initially, and will probably out-do him.
Alas. Neither of our children (now aged 31 and 27) ever showed the slightest interest in learning photography. This might have been because when they were just little Muchkins, I'd wake them up at 4:00 am and schlepp them downtown to photograph them at various interesting places in Toronto. Today, they and their sposes take all their snapshots with Cellphones or Point and Shoot cameras. I assume that if and when they have children, I'll be called on to do the "serious" pictures.