Every Child Learns Piano Differently
Every child learns the piano differently. There is no one-size-fits-all method in children's piano. Teachers and publishers will tell you there is a single method, the conventional one, but there is not. No one method, including ours, is guaranteed to get your child interested in the piano.
Don't pin your hopes on the miracle method. Kids vary in personality, and age has almost complete control of a kid's brain development. These two variables alone, personality and age, make a "uni-method" a laughable untruth. Because of this, most kids fail at the piano.
Fit The Method To The Child
The conventional methods are marketed as if you are sending your child to Juilliard, so your kids need to learn their scales the right way, right now. Faber, Bastien, Alfred and many more methods are offered as the only proper way to start.
I'll tell you the truth about these book methods. Kids hate them until they are absolutely sure that this is their way forward. There are traditions two hundred years old to which your child will be subjected, some of them quite logical. All will be held up to you as the only way to play properly. That's not going to happen, because your child is childish.
Find A Patient Teacher
What's going to happen, in a good outcome scenario, is that your child will be lucky enough to find a good, patient teacher. Such a lucky student will thus take an interest in the piano, fueled by themselves, and not fueled by your entreaties to practice, or the iron hand of an unforgiving piano teacher.
Either teach the child to take an interest in the piano, or begin the force-feeding process of reading music. Guess which works better.
Use Humor, Not Fear
The one factor that holds them back is fear. Fear of failing at some task, fear of not pleasing the teacher. You should eliminate that fear and replace it with a forgiving sense of humor. Mistakes are inevitable and as numerous as weeds. So laugh and forgive, take notice and move on.
Kids are smart. They notice what you say is a mistake. Their only fear is your anger. What I'm after is a kid who is willing to try anything at the piano, then fail at it, and scrape themselves up again and try one more time. That's what it takes to learn the piano, not mindless rote discipline. You need a scientist, not a soldier.
Play To Their Strengths
Some kids are good at chords. So give them pop songs that extend their knowledge of chords. For the rare kids that like reading music, go from page to page and they will accept it if they know you will stop any time they ask, and just play music.
Younger kids often play with one hand, so indulge them and forget about chords for now. Your job is to remove obstacles to their enthusiasm, not set up more.