Chapter 15:
Introduction to scales

Scales are for the brain, not the fingers. Don't play like a robot.

What scales are good for—and bad for

Scales describe the notes

Scales are the foundation of harmony and melody. Every key is derived from a scale. The notes in the key are the notes of the scale, and the chords in the key are harmonized from the scale. See Chapter 6. Introduction to Western harmony for details.

Scales are immensely helpful for understanding music by reason. When practice time is governed by reason, and performance time is governed by habit and intuition, an understanding of scales can guide our practice so we develop useful habits and intuitions about sounds and how to produce them.

Scales are habit-forming

But practicing scales can also be dangerous. The danger is that when scales are practiced by rote, the creative and inquisitive mind gets lulled to sleep. Mindless repetition of scales digs deep ruts of habit in our nervous system, which makes improvisation sound mechanical and boring. It can be hard to avoid this trap.

The way to avoid accidentally programming ourselves into scale-playing robots is to always be mindful when practicing scales. We have to think about each note as we play it, and slow down to give ourselves time to do so. See “practice mindfully” below for details.

What is a scale?

A scale is an ordered collection of tones.

Scale degrees

The tones in a scale are numbered in order, from lowest pitch to highest. These numbers are called “scale degrees”. The first degree of a scale is called the “tonic”. The other degrees are named for their interval from the tonic.

Scale degree numbers are sometimes written with “hats” (1̂, 2̂, b3̂, etc.) when it adds clarity, to distinguish them from other numbers.

Diatonic scales

Most scales in Western music are “diatonic”, which means they have seven notes, with five whole tone intervals and two semitones spaced as far apart as possible.

Scale formulas

Scales are defined by their intervals, either between degrees (ex. T-T-S-T-T-T-S), from the tonic (ex. 1-2-3-4-5-6-7 or 1-2-b3-4-5-b6-b7), or by the location of semitones (ex. semitones at 3-4 and 7-1).

For example, the major scale is a seven note diatonic scale with semitones between degrees 3-4 and 7-1. By definition, all the major scale degrees are major or perfect intervals.

Major scale intervals

  T T S T T T S
1 2 3 4 5 6 7 1

As another example, the natural minor scale is a seven note diatonic scale with semitones between degrees 2-b3 and 5-b6.

Natural minor scale intervals

  T S T T S T T
1 2 b3 4 5 b6 b7 1
C D Eb F G Ab Bb C

Assembling scales on one string

The simplest way to visualize a scale is on a single guitar string. The scale semitones and tones are one and two frets apart.

C major scale on second string.
C major scale on second string.
C natural minor scale on second string.
C natural minor scale on second string.

Assembling scales across strings

Assembling a scale across strings requires knowing where to find semitone and whole tone intervals on neighboring strings.

Remember that the intervals between all strings are the same (a perfect fourth), except the interval between strings 2-3 (the “third rail”) is one semitone smaller (a major third).

When interval shapes cross the “third rail” between strings 2-3, the higher pitched note is pushed forward by one fret. When descending, another way to think about it is that the lower pitched note is pushed back by one fret.

Semitone and whole tone on neighboring strings.
Semitone and whole tone on neighboring strings.
Intervals on neighboring strings.
Intervals on neighboring strings.

As a trick for finding the next scale degree on the neighboring string, notice that when playing the lower note with the little finger, the whole tone up on the neighboring string is under the index finger. A whole tone across strings spans four fingers. To reach the semitone instead, stretch the index finger back one fret. (A whole tone across strings 3-2 spans only 3 fingers, ex. little finger to middle finger.)

CAGED scale forms

Scales are typically taught in a variety of “forms” or “shapes”, with different teachers using different forms having often contradictory names.

This book focuses on scale forms based around CAGED chord shapes. This is practical because it integrates with the chords we are actually playing, and we gradually develop an understanding and muscle memory for chords and scales blended together. This blended intuition helps things flow when improvising.

Anchoring scales on CAGED roots also results in a clear and obvious way to name scale forms, like “C form” or “A form”, rather than using ambiguous terms like “form 1” or “position 5-2”.

To assemble a scale on a CAGED form, put the first note of the scale on the lowest root of one of the CAGED chord shapes, and assemble the scale across the strings without moving the hand out of position.

See Chapter 7. Practical CAGED grips for more on CAGED chord shapes.


A 7-note scale with the tonic repeated at the octave can be split into two 4-note sequences called tetrachords. As more scales are learned, it can become easier to think in tetrachords rather than full scale sequences, since scales often share tetrachords.

The two tetrachords of a scale can be played on guitar in a convenient box shape, with the upper tetrachord to the the left of the lower, on every pair of strings except for 2-3.

Here are the two tetrachords of the major scale.

Major scale tetrachords
Major scale tetrachords

In the major scale, both tetrachords are the same, which is not the case with all scales.

Comparing tetrachords with a known reference scale is a good way to get familiar with a new scale.

For example, compare the major and melodic minor tetrachords:

Major scale tetrachords
Major scale tetrachords
Melodic minor scale tetrachords
Melodic minor scale tetrachords

Compared to the major scale, it’s easy to see the melodic minor differs by having a minor third.

Some common tetrachord names:

major T-T-S 1-2-3-4 C-D-E-F
minor T-S-T 1-2-b3-4 C-D-Eb-F
hijaz / upper harmonic minor S-TS-S 1-b2-3-4 C-Db-E-F
phrygian S-T-T 1-b2-b3-4 C-Db-Eb-F
lydian T-T-T 1-2-3-#4 C-D-E-F#

Practicing scales

Practicing mindfully

The way to avoid accidentally programming ourselves into scale-playing robots is to always be mindful when practicing scales. We have to think about each note as we play it.

For example, which note is it? What scale degree / interval from the tonic? What’s the interval from the root of the chord? How does it sound and feel in this context? (If it sounds really good, play it again!)

It’s not necessary to think about all of this for each note, but it’s critical to think about something; to engage our brain and not just our fingers.

This also means we have to slow down when we practice scales. There’s no time to think about each note if we’re shredding at top speed. Perhaps surprisingly, practicing slowly and intentionally like this is actually the most effective way to develop speed. At performance time, with the analytical mind mostly turned off, our fingers are unleashed to repeat the habits that we’ve formed during practice. And if the habits are deep, it’s surprising how fast we can execute them.

The trick is to slowly and carefully form the intended habits during practice, which sound good to our ear and which carefully exclude sloppiness and mistakes. It’s like carving a rut into the dirt to direct the future flow of rain water to irrigate the crops.


Scales can be practiced most effectively by chunking. This means breaking information into chunks, learning each chunk separately, then learning them in combination as a larger chunk.

Most people can hold about 5-7 things in mind at any one time. Chunking makes optimal use of this capability.

It’s important to take the necessary time to learn a chunk thoroughly before trying to combine it with other chunks.

Focus on intervals, not scale shapes

Don’t waste any effort trying to memorize the shapes of scales on the fretboard.

Focus on the intervals between the notes instead. How they sound, where to find them, what they mean.

Gradually it will become apparent that our fingers have learned the scale shapes on their own, wired into the sounds and feelings of the intervals.

It’s efficient to learn something without effort in this way. But more importantly, this approach makes it possible to direct the fingers by thinking of a sound or an interval and have the fingers place themselves automatically, much as we can write a word on paper without thinking of the specific squiggles of our fingers. This ability is useful for playing by ear and improvising.

Practicing in this way strengthens neural pathways in the brain, which can then be reused automatically at performance time. It’s like digging an irrigation ditch so that when the rain falls it is routed to water our plants. Or like clearing a pathway in a forest that will later be run downhill in the dark.

Ascending and descending, slowly

From the tonic note, thoughtfully assemble the scale from its intervals as far as it can go ascending and descending. Play slowly and mindfully, knowing each note before moving on to the next. Gradually learn where each interval is in this form. Aim for perfection. Any mistakes should be repeated over correctly many multiples of times. Think of carving a niche in the dirt for irrigation, or starting a saw cut in a piece of wood.

Tunes and licks

While ascending or descending, switch directions at will to prevent boredom and make little melodic phrases. This may reveal melodies from tunes long buried in deep memories. It can be surprising how many popular, classical, folk, and religious traditional songs consist largely of snippets of scales.

Sounds that we like should be replayed, slowly, thoughtfully, and repeatedly, so they will become part of our personal style.

Patterns and arpeggios

It’s worth practicing scales in the following patterns. They sound good, it’s more interesting than just playing ascending and descending, and a lot of melodies incorporate these patterns.

  • Thirds: Ascending thirds up and down, then descending thirds up and down
  • 3-note diatonic arpeggios: ascending up and down, then descending up and down
  • Cyclical quadruplets (3123, 3213, 1321, 1231)