A necessary part of any course in music theory is the study of the circle of fifths. To some it may be intimidating but the circle of fifths is nothing more than a method of organizing the 12 keys in the world of music. This organization is done according to the number of flat notes or sharp notes a particular key contains. In our study of the 12 keys earlier in this course we separated the keys into flat keys and sharp keys, now we are going to further study, organize and memorize these 12 keys according to their key signature, or the number of flats or sharps they contain.
Below is an illustration of the circle of fifths, the 12 key signatures in music theory and inside the thick black circle is the second main concept of this lesson, the relative keys. Study the illustration below and for those of you who are quite serious about this course do your best to copy the circle of fifths in your music writing notebook.
Now that you know what the circle of fifths looks like, let’s understand the logic behind it. Starting with the sharp keys and going clockwise starting from “C”, each one of the keys is separated by the interval of a fifth, that means that the fifth note in the key of C is G, the note that is 5 scale steps away, that’s why its called a fifth. In our circle the first key is the key of C the key containing no sharps and no flats. The second key in our clockwise motion around the circle is the key of G, the note that is 5 major scale steps away from C and the crux of the matter is that G is the key which has one sharp.
Below is a table illustrating the keys in the world of music which contain sharp notes, notice that each new key has one more sharp than the previous key also notice that each new key is the fifth note of the previous key. So to continue with that thinking the next key in our clockwise motion around the circle of fifths is D. is the key which contains two sharps. That note D is also the fifth note of the G Major scale, D is separated from G by the interval of a fifth (5 major scale steps).
|
Degree |
I |
II |
III |
IV |
V |
VI |
VII |
I |
| Key of C: 0# |
C
|
D
|
E
|
F
|
G
|
A
|
B
|
C
|
| Key of G: 1# |
G
|
A
|
B
|
C
|
D
|
E
|
F#
|
G
|
| Key of D: 2# |
D
|
E
|
F#
|
G
|
A
|
B
|
C#
|
D
|
| Key of A: 3# |
A
|
B
|
C#
|
D
|
E
|
F#
|
G#
|
A
|
| Key of E: 4# |
E
|
F#
|
G#
|
A
|
B
|
C#
|
D#
|
E
|
| Key of B:5# |
B
|
C#
|
D#
|
E
|
F#
|
G#
|
A#
|
B
|
| Key of F#: 6# |
F#
|
G#
|
A#
|
B
|
C#
|
D#
|
E#
|
F#
|
To make sure you understand this concept let’s examine the third key ing in our Circle of fifths. Following the principal of clockwise motion the next key would be the key containing three sharps, the key of A. The A note would also be the fifth note of D. the previous note in our circular motion. This A note is of course the root note of the key containing three sharps (A major) and the key which occupies the third space from the top of the circle of fifths. This then is the pattern associated with and logic behind the circle of fifths.
The circle of fifths is also called the circle of fourths and either name is quite correct. Below is a table which illustrates the keys in our musical world which contained flat notes.As you study the table be low the key on the top is of course C the key containing no flats. If you count up for major scale degrees you will arrive at the F note, F is the fourth of C and F is also the key containing one flat. In the circle of fifths F is also the key directly to the left of C. Upon examining the key of F you will notice that the fourth note in the key of F is B flat. And according to our newly established pattern B-flat is the key containing two flats and it is also the key directly to the left of F in our circle. The circle of fifths is also commonly called the circle of fourths but most people think of it as the circle of fifths.At the risk of being repetitive I urge you to get your music writing notebook and copy down these two tables and also the circle of fifths and its key signatures as a means of accelerating your learning process.
|
Degree |
I |
II |
III |
IV |
V |
VI |
VII |
I |
| Key of C: 0b |
C
|
D
|
E
|
F
|
G
|
A
|
B
|
C
|
| Key of F: 1b |
F
|
G
|
A
|
Bb
|
C
|
D
|
E
|
F
|
|
Key of Bb: 2b |
Bb
|
C
|
D
|
Eb
|
F
|
G
|
A
|
Bb
|
| Key of Eb: 3b |
Eb
|
F
|
G
|
Ab
|
Bb
|
C
|
D
|
Eb
|
| Key of Ab: 4b |
Ab
|
Bb
|
C
|
Db
|
Eb
|
F
|
G
|
Ab
|
| Key of Db: 5b |
Db
|
Eb
|
F
|
Gb
|
Ab
|
Bb
|
C
|
Db
|
| Key of Gb: 6b |
Gb
|
Ab
|
Bb
|
Cb
|
Db
|
Eb
|
F
|
Gb
|
The Relative Minor Keys
At this point in this course the next essential concept you must learn is that of relative minor keys. Simply put each and every one of the 12 keys in music has a relative minor with which it shares a key signature. Study the graphic below until you understand that the key of C major with its bright happy sound and the key of A minor with its sad and mysterious one share a key signature.
To start let’s solidify our understanding of A minor, how it relates to A major and why the key of A minor has no flats or sharps. Because they share a root note, the keys of A minor and A major are called Parallel
By the same token the keys of C major and C minor are called Parallel Keys because they also share a root note. Study the diagram below to solidify your understanding of the two keys of C major and C minor and how they relate to each other. As you study this diagram remember the basic rules concerning major and minor scales: a major scale has half steps between degrees three and four and also between degrees seven and eight, a minor scale has half steps between degrees two and three and also between degrees five and six.
Now you we can comfortably moved to the subject of relative minors. The diagram below compares the key of C major with its relative minor, the key of A minor.As you have no doubt gleaned from the two diagrams you have just studied both the keys of C major and a minor contain no flats are sharps, in that regard they are the same and therefore they share a key signature. When a major scale and a minor scale share a key signature they are called relatives or relative keys. The interactive diagram below will help you understand the relationship that C major and A minor share.
Table Of Sharp Keys And Their Relative Minors
|
Major Keys
|
C
|
G
|
D
|
A
|
E
|
B
|
F#
|
|
Relative Minor Keys
|
Am
|
Em
|
Bm
|
F#m
|
C#m
|
G#m
|
D#m
|
| Key Signature |
 |
 |
 |
 |
 |
 |
 |
Table Of Flat Keys And Their Relative Minors
|
Major Keys
|
C
|
F
|
Bb
|
Eb
|
Ab
|
Db
|
Gb
|
|
Relative Minor Keys
|
Am
|
Dm
|
Gm
|
Cm
|
Fm
|
Bbm
|
Ebm
|
| Key Signature |
|
 |
 |
 |
 |
 |
 |