I'd like to share something that just spawned a real AHA! moment for me last week. 
I was working on my closed position scales with a pretty basic scale fingering 
like this:


|---|-x-|---|-x-|-R-|---|-x-|---|
|---|-x-|---|-x-|-x-|---|-x-|---|
|---|-x-|---|-x-|---|-x-|-R-|---|
|---|-R-|---|-x-|---|-x-|-x-|---|

So I started looking at the pattern and thought Hmm. The root note starts on the 
first finger and the pattern for the first two strings is the same. The root note 
ends up on the 4th finger and then there are 2 more strings with the same pattern.

Also, I noticed that if I look at the finger where the root note ends up (4th finger 
for the first 2 strings, 3rd finger for the next 2 strings) that the half step is 
the fret right before the root note. By that I mean in this scale

|---|-x-|---|-x-|---|-x-|-R-|---|
|---|-R-|---|-x-|---|-x-|-x-|---|

the root ends up on the 4th finger and the half steps in the fingering are right 
before the 4th finger. In this scale

|---|-x-|---|-x-|-R-|---|-x-|---|
|---|-x-|---|-x-|-x-|---|-x-|---|

The root ends up on the 3rd finger and the half steps in the pattern occur right 
before the 3rd finger

I also play an instrument called The Chapman Stick www.stick.com And in the book 
for that instrument there is a concept of "4ths into infinity". The stick is 
tuned in ascending 4ths. More importantly all the strings are separated by the 
same interval, just like on a mandolin and unlike a guitar (which is 4ths except 
for that Major 3rd interval from the 2nd to 3rd string)

On an instrument with equal intervals between the strings like Stick, mandolin, 
violin, viola, cello, bass etc. you can imagine an instrument with an infinite 
number of strings all in ascending 5ths (in the case of a mandolin) If we build 
our scales now we see something really cool.


|-x-|---|-x-|---|-x-|-R-|---|---|---|
|-R-|---|-x-|---|-x-|-x-|---|---|---|
|-x-|---|-x-|---|-x-|---|-x-|---|---|
|---|-x-|-R-|---|-x-|---|-x-|---|---|
|---|-x-|-x-|---|-x-|---|-x-|---|---|
|---|-x-|---|-x-|-R-|---|-x-|---|---|
|---|-x-|---|-x-|-x-|---|-x-|---|---|
|---|-x-|---|-x-|---|-x-|-R-|---|---|
|---|-R-|---|-x-|---|-x-|-x-|---|---|
|---|-x-|---|-x-|---|-x-|---|-x-|---|
|---|---|-x-|-R-|---|-x-|---|-x-|---|
|---|---|-x-|-x-|---|-x-|---|-x-|---|
|---|---|-x-|---|-x-|-R-|---|-x-|---|
|---|---|-x-|---|-x-|-x-|---|-x-|---|
|---|---|-x-|---|-x-|---|-x-|-R-|---|
|---|---|-R-|---|-x-|---|-x-|-x-|---|

I wrote out 16 strings but notice that the pattern repeats after 8 strings. You 
only have to memorize 8 strings. Also notice that there are only 4 actual 
fingering patterns. That is, the first 2 strings (counting from the bottom) are 
the same pattern. The next 2 strings have the same pattern. The next two share 
the same pattern, and then there is one string of all whole steps and then the 
whole thing shifts down one fret and repeats.


Starting with a scale on the 1st finger we can play across our infinite string 
mandolin and after 2 strings we end up with a root on our 4th finger. 2 strings 
later we end up with a root on our 3rd finger. 2 strings later we end up with a 
root on our 2nd finger. 2 strings later we end up with a root on our 1st finger 
and then the pattern starts all over again. So instead of thinking of your 
scales as 4 different scales, with each one starting on a different finger, 
think of it as ONE BIG SCALE that spans 8 strings and then repeats forever!

This not only makes it easier to visualize and learn your scales, but it has 2 
huge advantages:

1. Shifting:

Let's say you want to play up the neck. You could play the first 7 notes with 
the root starting on the 1st finger and then instead of playing the next note 
with your 4th finger you can just shift up and play that note (for example) 
with your 2nd. From that point you just continue on with the pattern

|---|---|---|---|-R-|---|-x-|---|-x-|-x-|---|---|
|---|---|---|---|-x-|---|-x-|---|-x-|---|-x-|---|
|---|-x-|---|-x-|---|-x-|-R-|---|-x-|---|-x-|---|
|---|-R-|---|-x-|---|-x-|-x-|---|---|---|---|---|

In tab that would be

|---------------------------------------------------5--7--9--10-|
|--------------------------------------5--7--9--11--------------|
|--------------2--4--6-shift-7--9--11---------------------------|
|--2--4--6--7---------------------------------------------------|
fingering
1 2 3 4 1 2 3 2 3 4 1 2 3 4 1 2 3 4


2. Modal playing:

Instead of putting little x's on our chart let's number them by scale tone:

|-5-|---|-6-|---|-7-|-R-|---|---|---|
|-R-|---|-2-|---|-3-|-4-|---|---|---|
|-4-|---|-5-|---|-6-|---|-7-|---|---|
|---|-7-|-R-|---|-2-|---|-3-|---|---|
|---|-3-|-4-|---|-5-|---|-6-|---|---|
|---|-6-|---|-7-|-R-|---|-2-|---|---|
|---|-2-|---|-3-|-4-|---|-5-|---|---|
|---|-5-|---|-6-|---|-7-|-R-|---|---|
|---|-R-|---|-2-|---|-3-|-4-|---|---|
|---|-4-|---|-5-|---|-6-|---|-7-|---|
|---|---|-7-|-R-|---|-2-|---|-3-|---|
|---|---|-3-|-4-|---|-5-|---|-6-|---|
|---|---|-6-|---|-7-|-R-|---|-2-|---|
|---|---|-2-|---|-3-|-4-|---|-5-|---|
|---|---|-5-|---|-6-|---|-7-|-R-|---|
|---|---|-R-|---|-2-|---|-3-|-4-|---|

Quick Mode review: If you play a major scale (let's use C Major for our example. 
No sharps, no flats) starting on the root you have the Ionian mode. If you play 
the exact same notes but start on the 2nd scale tone (D to D with no sharps or 
flats in our example) then you are playing in the dorian mode.

In our example using the key of C we would have played C Ionian and D dorian.

Each mode starts on a different note of the major scale. If you take the 1st, 
3rd, 5th, and 7th note of that modal scale you get a different chord. I'll 
list the scale tone the mode starts on, the name of the mode, the chord that 
the mode produces, and the specific chord that would be produced if we were 
playing the modes in the key of C

Root Ionian Major 7th CMaj7
2nd Dorian Minor 7th Dm7
3rd Phrygian Minor 7th Em7
4th Lydian Major 7th FMaj7
5th Mixolydian Dominant 7th G7
6th Aeolian Minor 7th Am7
7th Locrian Minor7th b5 B m7 b5

Here's the big AHA! moment. That means that all your scales, all your modes, 
are really just a small section of this ONE BIG SCALE. Take the Dorian mode for 
example. That mode is based off of the 2 note of the major scale. So we'll take 
a random note like the A on the 7th fret of the D string and we'll say that we 
want to play an A Dorian mode scale based on that note. Well, which finger do 
you want to start with? Let's just say we want to start with the 2nd finger. 
So we look at the chart above (or we memorize the chart above) and
find a position where the number 2 falls on the 2nd finger. If we take that 
portion of our 5ths into infinity scale and place it on our fingerboard such 
that the 2nd finger falls on the 7th fret of the D string then that gives us 
this scale:

|---|---|---|---|-O-|---|-x-|-x-|---|-x-|---|---|
|---|---|---|---|-x-|---|-x-|---|-x-|-x-|---|---|
|---|---|---|---|-x-|---|-O-|---|-x-|-x-|---|---|
|---|---|---|---|-x-|---|-x-|---|-x-|---|-x-|---|

I put an O where the A notes are (the root note of the A Dorian scale)

Every mode of every major scale in every key located at any position on the 
fretboard is derived from THIS ONE BIG SCALE! If you learn this simple repeating 
pattern then you've learned every modal scale for any key starting with any 
finger and located anywhere on the fretboard. This is the unified
theory of mandolin scales.