I respect this, and it is the tried and true safety regimen. But I have found that youngsters have the attention span of brick, sometimes. And a few of them have been down right insulted with a similar approach. One of the reasons I like the Henry is that it essentially offers one round at a time, and while they are cycling the rifle, I can offer encouragement and reminders, while standing over their shoulder, close enough to stop muzzle sweep. I can also run 22 quiets for the first magazine so that with just foamies, we can converse. Most of the kids I have taken really enjoy the Golden Boy.
When children are present on the firing line, they are allowed to be there because they are capable of behaving like adults. Of course, I watch them like a hawk, and keep them separate from the guns and ammunition when they are out of arms reach, but I do not treat them like children. I address them like competent and capable people, and if they don't behave that way, then they are done shooting for the day. Same rules also apply for adults.
Now I do believe that everyone should have some fun, and I am not out to make shooting boring, but if you have no attention span, then its cap guns for you. The focus of the first day needs to be on safety. And it is an important lesson that actual shooting is not like a video game or an action movie.
With all of that said, the rule about one round per magazine is particularly for semi-autos. With first time shooters, semi-autos are sort of an accident waiting to happen. A manual action is far preferable for the first time, since if someone has a startled or clumsy reaction to the shot, they are not already holding a live gun. With a manual action, I would still start with one round, but I might move to several rounds in the magazine after only about three single shots.
I really like the Henry lever action for beginners. It is much safer than a semi-auto, but is also lots of fun for shooters of all levels. The fact that it will feed quiet rounds is just an extra bonus. I would always prefer that beginners start with lever or bolt action .22 rifles, and then a .22 revolver, but often those firearms are not available. If the first shots need to be done on a semi-auto, then one round at a time keeps everyone safe. And if children are insulted by the single rounds, then maybe they need to see me teach an adult beginner first. I always start adults with one round at a time too.