A cycle-of-fifths chart is a powerful tool for decoding many chord progressions. The one shown below arranges major triads on the outer ring, the roots moving up a perfect fifth with each clockwise step. The inner ring shows the relative minor triad for each major triad. The minor triads are also arranged in clockwise steps of a fifth.
Memorize this: If you mark the chords from a chord progression on the cycle-of-fifths chart, they’ll often fall into three adjacent slices of the circle. When that happens, the positions of the chords reveal each chord’s Nashville numbers as shown:
Recall that the key of the song doesn’t always correspond to the I chord. For example, if we apply this analysis to “Little Wing,” the E minor triad sounds like “home”. The E minor triad sits in the vi position, making the key E natural minor.
The chord that sounds like “home” also tells us the mode of the song. As we just saw, “Little Wing” is in the Aeolian mode because the “home” chord is in the vi spot. If the chord in the I spot sounds like home, the song is in the Ionian mode. ii is Dorian, iii is Phrygian, IV is Lydian, and V is Mixolydian.
When this process doesn’t work, or there are “extra” chords, it can mean that some chords are borrowed from another key or that the song modulates from one key to another. Try analyzing each section of the song separately, and you might find that it makes sense to use a different scale in the chorus than in the verse.
When in doubt, trust your ears. Come up with a few hypotheses for what might sound good, try them out, and pick the one you like the most.
Blues music is primarily built on dominant seventh chords. A basic 12-bar blues has three chords—I7, IV7, and V7—and no two of those chords fit inside a single major scale. Much of traditional music theory simply doesn’t apply to this situation, including the analysis of a song’s key from 8-1.
In this module, we’ll focus on a basic 12-bar blues in A. The chords will be A7 (I7), D7 (IV7), and E7 (V7). This is the basic progression in Nashville notation:
and in the key of A:
Blues players use a variety of scales to navigate the blues. One approach is to use the minor pentatonic (or minor blues) scale that corresponds to the key of the song (i.e., the root of the I chord). It’s also common to match scales to individual chords. You can usually play either a minor or major pentatonic scale that matches the root of any chord. Traditional theory suggests that the Mixolydian mode fits a dominant seven chord well, so that’s yet another option.
These are the most common scale choices for a blues in A (anywhere you see a pentatonic scale, you can substitute a blues scale of the same key):
| A7 (I7) | D7 (IV7) | E7 (V7) |
|---|---|---|
| A minor pentatonic | A minor pentatonic | A minor pentatonic |
| A major pentatonic | D major pentatonic | E major pentatonic |
| A Mixolydian | E minor pentatonic |
It is a good idea to decide ahead of time which scales you intend to use over each chord in the progression. I call this a flight plan, and we’ll talk more about it soon.
There are five remaining notes on the fretboard to memorize: the sharps and flats. In music notation, if you put a sharp symbol (#) after a note name, it raises the pitch of that note by one semitone, or one fret. A flat symbol (♭) similarly lowers the pitch of the note by one semitone.
The five notes we haven’t covered yet each go by two names: A#/B♭, C#/D♭, D#/E♭, F#/G♭, and G#/A♭. Technically, B# is the same pitch as C, C♭ is B, E# is F, and F♭ is E, but you won’t see those used much in practice. There are some cases in music theory where which note name you use matters, but for purposes of this course, the note names in each pair are interchangeable.
One way to find these notes on the fretboard is to find the note without a sharp or flat and then move up or down a fret to the target note. It’s fine to start out doing that, but it’s a good idea to practice finding them enough that you end up knowing them by rote.
Exercise 1: On a single string, practice finding all of the notes in the cycle of 4ths:
B - E - A - D - G - C - F - Bb - Eb - Ab - Db - Gb. Do this on each of the six strings.
Exercise 2: On a single string, practice finding all of the notes in the cycle of 5ths:
F - C - G - D - A - E - B - F# - C# - G# - D# - A#. Do this on each of the six strings.
Exercise 3: Play the chromatic scale with one note per string (e.g., play an A on the low E string, A# on the A string, B on the D string, etc.), reversing direction when you reach one of the outer strings and continuing up the scale. You can start on any note in the scale.
Exercise 4: Repeat Exercise 3, but playing down the chromatic scale.
Memorize this: There are two blues scales: the minor blues scale, which is what most people think of, and the major blues scale. Conveniently, they both share the exact same fingering patterns, which are simple to visualize by adding one note to the rectangle and stack.
In the minor blues scale, the added note is the #4 or ♭5. In the major blues scale, it is the ♭3. In both scales, the added note is best treated as a passing note. It is rarely emphasized.
To improvise effectively in a blues setting, you will need to keep track of which chord is being played, and you’ll need to find its target notes relative to the scale you have chosen to play.
Memorize this: When playing a major pentatonic (or major blues) scale over a dominant seventh chord with the same root, these are the chord tone targets and recommended bends inside the rectangle and stack:
Memorize this: When playing a minor pentatonic (or minor blues) scale over a dominant seventh chord with the same root, these are the chord tone targets and recommended bends inside the rectangle and stack:
Memorize this: When using the minor pentatonic corresponding to the song’s key over the entire progression, the target notes change depending on the chord:
The idea of combining the minor and major pentatonic (or blues) scales into a single hybrid scale is often discussed amongst players. Combining these scales results in a monster scale with 9 notes, which does not lend itself to playing melodically.
Rather than learning a new hybrid scale, I recommend switching back and forth between the two scales. Using the rectangle and stack method, this is possible even midstream during a single phrase.
To pivot from one scale to the other, visualize a major stack and a minor rectangle sharing a single root:
or a major rectangle and minor stack with their roots aligned:
One classic way to mix these scales is to play a call and response where the call is in major pentatonic and the response is in minor. This is often done over the opening four bars of I7 in a 12-bar blues.
There are five different transitions between pairs of chords inside a 12-bar blues: I7→IV7, IV7→I7, I7→V7, V7→IV7, and V7→I7. It is worth practicing each transition individually.
Exercise 1: Practice transitioning from I7→IV7 using a looped backing track. Using a single rectangle, for each chord change, play two approach notes from the pentatonic scale leading to a chord tone of the new chord.
Exercise 2: Repeat Exercise 1 using a stack.
Exercises 3-4: Repeat Exercises 1-2, allowing yourself to play more freely, but still landing on a chord tone on each chord change.
Exercises 5-20: Repeat Exercises 1-4 for each of the four other transitions.
Exercises: 21-n: Repeat the previous exercises, allowing yourself to move more freely around the fretboard. Be sure to practice pentatonic Form 1, Form 2, and Form 4, and explore the diagonal pathway that connects Form 1 to Forms 2 and 5. These are the areas that blues players most often explore.
The goal of this module is to be able to improvise over a 12-bar blues in A. As with every chord progression you intend to improvise over, it is a good idea to spend some time listening to the chord changes without your guitar until you are confident that you always know which chord is being played and which one is coming up next.
Here is the recommended flight plan we’ll be using. It divides the 12-bar blues into six two-bar phrases, each using a single scale. The last two phrases will be the trickiest because the target notes change for each measure:
| Phrase | Measures | Chords | Scale | Targets |
|---|---|---|---|---|
| 1 | 1-2 | A7 | A major pentatonic | I7 |
| 2 | 3-4 | A7 | A minor pentatonic | I7 |
| 3 | 5-6 | D7 | A minor pentatonic | IV7 |
| 4 | 7-8 | A7 | A minor pentatonic | I7 |
| 5 | 9-10 | E7→D7 | A minor pentatonic | V7→IV7 |
| 6 | 11-12 | A7→E7 | A minor pentatonic | I7→V7 |
Exercises 1-6: Practice improvising each of the six phrases in isolation using a backing track. Experiment with different target notes and different areas of the neck.
Exercises 7-10: Practice improvising in blocks of four bars using backing tracks.
Exercise 11: Practice improvising over the entire 12-bar blues using a backing track.
Blues in A
A · 90 BPM · 12 chords · 32.0s loop
The whole 12-bar form at 90 BPM, divided into the three four-bar sections the exercises work through. Click a section name to loop those four bars for Exercises 7 to 10; drag across any two chords to loop just that pair for the six two-bar phrases. Every exercise in this section comes out of this one track, so you can go from a single phrase to the whole form and back without stopping the music. The flight plan under the chart is the one from the table above — change any bar's scale and the bars after it follow, or reset it back to the lesson's.
Keep in mind that the flight plan used in this module is just a suggestion. Create your own flight plans and experiment to find the combination of scales and chord tone targets you like.