Modes: The Other Side of Scales
The first place to deepen your understanding of scales is right back at the major scale. As a musician, you may have heard the term modes. Many classical musicians don't deal with modes early on in their study, but jazz and rock players do. There are several reasons for this musical divide, which will become clear as you learn more about modes.
The simplest definition of a mode is that it is a displaced major scale. First, what does the term displaced mean? Take the F major scale: F–G–A–B–C–D–E–F. As you know, what makes it an F major scale is that the note F (the tonic degree) has the most weight; the scale wants to stop on the high F when you play it.
Now, what if you were to use the same vocabulary—that is, use the same F–G–A–B–C–D–E–F pitches (the F major scale)—but make a different note the root? What if the scale looked like this: D–E–F–G–A–B–C–D? If the D sounded like the root note (which is based on the context of the piece), then you have an official mode. You have a bit more than a mode, actually.
If you reread the last paragraph, you'll notice that an F scale is spelled from D. Is there a special relationship between F and D? Well, they are a sixth apart. Hmm, sixth note of a major scale, where have you heard that before? Try Chapter 5, in the section “Naming Minor Keys.” Remember the trick you learned there, to find the relative minor by going up six notes. Using this example, you can spell an F major scale starting from D, its sixth note, and it's called a mode. It's the D minor scale and a mode of F major.
So, you see that minor scales are also modes. The notes D–E–F–G–A–B–C–D form a D minor scale. A mode is formed when you call any other note besides the original root of the scale the root. The minor scale is just one example of a mode, one that you already know. But wait, there's more. Because a major scale has seven notes, there are seven modes.
Modes gained prominence during the golden age of the Gregorian chant, circa a.D. 900, when they were used to compose the melodies of vocal plain-chant. Modes stayed in use throughout the medieval era with some modification. The baroque and prebaroque periods used major and minor scales exclusively instead of modes. For all intents and purposes, modes lay dormant throughout the baroque era, the classical era, and most (but not all) of the romantic era.
Even though impressionist composers revived modes, it wasn't until jazz musicians started using them in improvisation and composition that modes became a useful part of music curricula. Today, all music students learn about modes, but the rock and jazz players tend to utilize them more frequently.