I have to jump in here and tell how I taught my boys to shoot.
I started them at about 6 years old. They were old enough to understand the basics of gun saftey and that they were never to get into my guns but could shoot all they wanted when I was along.
Anyway, they ALWAYS had ear protection, and I never talked to them about recoil or that there was even such a thing.
They started out shooting my 30-06 loaded with a buckshot for a bullet behind a few grains of Unique. And a 12 ga with just the wads. They did not know the difference between their loads and mine. Over the years I kept loading them up.
By the time they were around 9 years old they still were not big enough to hold up the guns to shoot offhand very well, but were shooting full strength loads while standing behind the bench with the guns on a rest.
When they were 10 I turned them loose with pellet guns. They had read some article about military Quick-Skill shooting. They then hacked the sights off of there pellet guns and started shooting air born targets, (glasses were a must). They were also allowed to shoot Starlings and could hit one on the wing every now and then.