This is from my new book Classical Guitar Technique: Essential Exercises, Scales, and Arpeggios. The 122 page book includes: Practice Routines, Tips, 100 Open String Exercises, 120 Giuliani Arpeggios, Scales, Slur Exercises, Shifts, Finger Independence, Barre, Tremolo, Common Harmonics, and much more.
Youtube Video Lesson Link (HD)
Scales with shifts that occur on open strings are the most practical and relevant scales in terms of application to repertoire. These scales also make excellent shift exercises and result in position shifts that sound very legato. The shifts can occur on any open string but in repertoire we often stay in first or second position until the shift is needed and, therefore, the shift usually occurs on the first or second string if possible.