This must be enjoyable and so rewarding to watch them learn and blossom with their music.
It is!
All three of my new students have had piano lessons in the past, but were bored with the standard, uninspiring curriculum.
I get them doing Jazz Improvisation on their first lesson. Two simple rules: Stay with the groove and stay in the key.
Otherwise they can do whatever they want. It frees them up from the goofy little songs in the instruction books.