One of the most classical piano studies is that of Ferdinand Beyer (1803-63). It is a classic German method, on which are formed many pianists of various generations.
In recent years, in particular for children, has been somewhat abandoned in favor of other publications, most appealing in writing music and images supplied.
However, it seems to me that the development of this area, as set by Beyer, is very effective for the progression of difficulty, is about learning to read music, both on the instrumental technique. What matters is the way you use a text: for example, I am using it by placing his pieces in a teaching methodology that emphasizes the rhythm, vocality and instrumental gestures, to the wellbeing of the person in the act of playing and, more generally, of making music.
In the original German some pieces are different, compared to the Italian editions: it is Volkslieder Germans really very nice.