Well, my next to youngest just passed an important milestone this afternoon. He had his seventh birthday over the weekend and I promised him that I'd start teaching him to shoot. This afternoon, he fired his first actual firearm. There was some training with BB guns and today he graduated to the smallest least dangerous thing that I own that can still technically be called a firearm.
Some time ago before any of my children were old enough to learn to shoot, I happened upon an old .22 short revolver that was intended to be a lady's purse pistol. To my eyes it said, small hands, small power... perfect kid's training gun.
I have a very methodical way of teaching these things. The very first thing a child has to learn is how to handle a firearm safely, respectfully and yet without fear. Once you can hand the child a firearm and they instinctively know to keep the muzzle pointed in a safe direction, how to proficiently operate the mechanism and not to drop it when it makes the loud noise... then you can move on to teaching them the fundamentals of marksmanship... safety first then proficiency.
Oh, one more thing. Since I posted a picture of his brother, I suppose I'll drop a picture of the youngest one out here too.