"Good improvisation communicates harmonic progression melodically. Effective melodies manipulate harmonic content through the use of guide tones and preparatory gravity notes, masterfully woven in systematic tension, release, and transparent harmonic definition."
Music theory is always a good tool to supercharge the process of understanding and internalizing the fretboard and scale/note relationships, but sometimes a novice can get lost without some kind of graphical tool to wrap the cerebral concepts around. Like trying to understand where Arizona is in relationship to Montana, let alone Vermont or Bangladesh, having the visual tool of a map or globe is a shortcut to the brain developing some kind of spatial reference.
We get into some pretty esoteric concepts around here with our high falutin' 'ii V7 I's and Lydian Dominants, and sometimes it doesn't hurt to check out tools that might make stepping out on the trip to mando mastery a little more efficient. Outside of a few chord charts and some FFcP TAB, we don't offer much in fret visuals, and perhaps it's time to recommend an outside source that might offer a strong graphical aid in grasping some of the basics of fretboard layout in the simpler concepts like Major and Minor Scales and Pentatonics, especially for beginners. Such is the case with Scott Sharp's "Fretboard Toolbox," basic chord, scale, and mode construction "jig."
More advance mandolinists will be farther down the road than this, but if you've just started this trip, or know someone that can play a little by ear and wants to really understand what she or he is doing, the materials would be a terrific first step.