Some children are remarkably sensitive to the differences between their at-home instrument and mine; they invariably do not practice their lesson. I never practiced my lesson, either, when I was young. I played all the time, but not the music I played at my lessons.

Today one of the mothers told me that her daughter works and works on things at home until she gets them right; but they are not the assigned music. "What should I do?"

"Nothing!"

The child is beginning to grasp the substance of music and how much fun it is to be delivering substance rather than repeating the notes in reliable (i.e. mechanical) sequence. I have no doubt whatsoever that she will soon be ready for substantial repertoire, not to poke at it but to really savor it.

The situation is totally different for children who play the violin or the guitar; they play their own instruments at the lesson.

"The" piano does not exist.