Keys

You own two or three shapes for the major scale now, all of them in G. Here’s the payoff for learning shapes with no open strings: slide the shape, and you’ve changed key. A key is just the set of notes you get by running the W-W-H-W-W-W-H recipe from a particular starting note — and your shapes are the recipe, so they work from any starting note.

Move the root, move the key

Take the position pattern from exercise two, rooted at fret 3 on the low E string: G major. Slide the whole fingering up two frets so the root lands on fret 5 — every note moves by the same distance, every step stays the same size, so the recipe is intact. You are now playing A major. Same hand, new key. That’s the entire mechanism.

Finding the key you want

Since the root names the key, knowing the notes along the two lowest strings turns “play in E flat” from a threat into an address lookup:

Low E string:  1=F  2=F#  3=G  4=G#  5=A  6=A#  7=B  8=C  9=C#  10=D  11=D#  12=E
A string:      1=A# 2=B  3=C  4=C#  5=D  6=D#  7=E  8=F  9=F#  10=G  11=G#  12=A

(Sharps double as flats: F# is the same fret as Gb.) Want C major with your position pattern? Its roots sit on the low E string — fret 8. Want it with a pattern whose lowest root is on the A string? Fret 3. Two strings’ worth of names unlocks every key for every shape you’ll ever learn.

The same melody in two keys

Proof that this works for music and not just scales. Here’s a famous melody as scale degrees — numbers only, so it lives in any key:

3 3 4 5 5 4 3 2 1 1 2 3 3 2 2

Work it out in G major around second position (degree 1 = G; you know where 1 through 5 live from the pattern). Take your time — hunting for it is the exercise. You’ll likely recognize the tune by the fifth note.

Now play the same numbers in A major: slide every finger two frets up and play the identical sequence. Same tune, same shape of rises and falls, just pitched higher. Singers ask for exactly this (“can we do it in A?”), and on guitar it costs two frets.

About sharps and flats

Running the recipe from G forced one sharp into the scale (F#). From A, it forces three. Each key carries its own set of sharps or flats — that’s all a “key signature” is, a packing list. You’ve been playing these altered notes all along without knowing, because the shapes encode them: keep the shape honest and the right sharps fall under your fingers by construction. Guitarists get this for free; pianists, who must refinger every key, regard it the way I regard your planet’s moon — with some envy.