Teaching Kid's Piano Is Like Herding Cats
Sometimes teaching kid's piano is like herding cats. Impossible. Think of a child at the piano as an animal, a sweet, bright little animal that needs your help. The best advice I ever saw for training animals (or children) was from the Horse Whisperer. He showed his method for getting the horse used to having a rope around their neck. Instead of jerking the rope suddenly to show who's boss, the Horse Whisperer first gently put the rope around the horse's neck, and then laid the rope on the ground, without holding it. When the horse noticed the rope, he tugged ever so gently on the rope. The horse looked up momentarily and noticed that someone had a rope. The horse grew to accept the rope without resenting the trainer. The rope was never used suddenly or with unexpected force.
Let Kids Be Kids
That is the type of common sense necessary to train both horses and child pianists.The first thing the wise trainer does is to allow the horse/child to be just that, a child. I don't correct kids constantly. That would be like jerking the rope. I choose my battles carefully. Once lessons get going, my constant concern is fingering. Try to get the kids to use common sense fingering. The rules alone are not enough. A child, like a horse, needs a little freedom to run.
Don't Force Fingering
I prefer to have kids seem to discover fingering for themselves, and I do this by gently but humorously tugging the rope (correcting) whenever they make a genuinely poor choice of fingering. Some piano teachers are on that rope every second, correcting fingering, posture, hand position, rhythm, sight reading, hand to hand coordination, on and on. And you wonder why kids quit the piano? Kids tire very quickly of the rope jerking relentlessly unless you learn to do it judiciously and always with humor.