A list of tunes to use for developing Melodic Expression, rated from easiest to hardest.
By Melodic Expression, I simply mean the ability to play a melody expressively. If a student wants to be able to improvise lines that are expressive, he must be able to play expressively, and one way to develop that is to play melodies of standard tunes.
Of course, "easy" and "hard" are relative, and vary from player to player, so the student is encouraged to build his own list.