Why not just take him out with one of your rods and use the time as a learning/ demonstrating time?
I just started taking my 4 and 7 yr. old sons out with one of my fly rods only--- (before we'd dunk worms under bobbers). Water full of sunnies, and a size 12 chernobyl ant will keep kids busy for days.....
I cast and 'present' the flies, I make sure the hook is set, and then I hand the rod to them and let them strip it in. I de-hook the fish, and set it into their hands to be gently released. They take turns retrieving and releasing-- every fish is a lunker, and there is no drama, whining, or crying allowed.
They know how a fish feels on the fly, they know how to release a fish gently, and they (I think) understand what 'cover' is-- my oldest (7 yrs) can spot areas in water that look like they'd hold fish.
I may be overly cautious, but I am hesitant to set my 7 yr. old out casting with a hook on the end just yet. We practice on the lawn (with a ball of yarn). He has a looooong way to go with form, but he is well on his way to becoming a fly fisher.