Multi-level songbooks are an excellent way for students to learn pieces via "scaffolding." These books are intended to be collections that students can grow with over a longer period of time. The base version (Version 1) correlates to Piano Pronto: Keyboard Kickoff, Version 2 correlates to Piano Pronto: Prelude, and Version 3 correlates with Piano Pronto: Movement 1. For motivated students you can have them learn one, two, or all three versions in succession, or have them work through a particular version (i.e. Version 1) of all the pieces and then circle back to learn the harder versions.