Using Major Scales
Now that you have worked with Major scales, the next step is learning just how to apply them to a piece of music. In order to do that you must understand the harmonized Major scale.
Very simply, to harmonize the Major scale you start with the scale notes and then build chords on each note by stacking thirds. Doing this for the C Major scale in triads we get:
C Dm Em F G Am and Bº
If we were to go to four note chords we get:
Cmaj7 Dm7 Em7 Fmaj7 G7 Am7 Bm7-5
Usually, these are referred to by roman numerals based on their position in the scale:
Cmaj7 is I, Dm7 is II, Em7 is III, Fmaj7 is IV, G7 is V, Am7 is VI, Bm7-5 is VII
So what we see here is that the I and IV chords are major sevenths, the II, III, and VI chords are minor sevenths, the V chord is a dominant seventh and the VII chord is a minor seven flat five chord, (also called a half diminished chord). The good news is that this sequence is true for every major scale, so all that you have to do is plug in the names from the scale you want to determine what chords occur in that key.
If you play the scale starting on each note and going up an octave, you get a scale that allows you to "hear" each chord in the scale. To put it another way, you play from C to C to hear Cmaj 7, D to D to hear Dm7 and so on up to B. These are what you will hear referred to in music theory as modes. C to C is the Ionian mode, D to D the Dorian mode, E to E the Phrygian mode, F to F the Lydian mode, G to G the Mixolydian mode, A to A the Aeolian mode, and B to B the Locrian mode.
Each of these "scales" contains the notes of the chord it is associated with, plus some others which we will discuss later. As long as the song stays in the same key as the key signature, these modes will work over the appropriate chord. To practice this, try playing each of these scales over the appropriate chord in all twelve keys. Listen to how each scale sounds against the chord. Play these in different intervals and try improvising over chord progressions as much as possible. Remember each I and IV chord will be associated with two keys and that each II, III, and VI chords with three keys. Listen to these differences and try to think of where one may work better than the other. Also pay attention to the mood or style that each of these may suggest.
This is a good starting point to begin to see how this works. Keep in mind that a song rarely stays in the same key, and that you will have to adjust your scales accordingly, the subject of next month’s article. You want to memorize this information so that you can play and not think. Try and think in terms of the roman numerals rather than chord names, as this will enable you to transpose much quicker.