Tetrachords – the little pieces to a rather large puzzle
A couple of years ago, a colleague told me that she teaches major scales to young students using tetrachords. This approach was eye opening for me and prompted me to try teaching this method to my 2nd level class for a couple of years. At the time it didn’t seem any more useful for that age group than relentlessly practicing scales over and over, until a few years later that group of kids, now in my advanced level, were learning more than just major scales. I got the idea to re-introduce them to tetrachords again and I started looking at all scales in a whole new way…
First of all, what’s a tetrachord? Simply put it’s 4 notes in a row.
Keeping things simple, let’s look at 2 tetrachords: Major and Minor
The Major Tetrachord is the first 4 notes of the major scale. Looking at it in terms of intervals: Whole Step, Whole Step, Half Step or WWH.
When we combine these Major Tetrachords we get major scales.
C Major Tetrachord + G Major Tetrachord = C Major Scale
G Major Tetrachord + D Major Tetrachrod = G Major Scale
D Major Tetrachord + A Major Tetrachord = D Major Scale
You can think of combining in 2 different ways:
1. The two tetrachords are a whole step apart (ex. from F to G) and this explains the extra whole step in the pattern we all learned as a kid
[W W H] W [W W H] – Now we can actually see the pattern.
2. As you can see by looking at the roots of each tetrachord: they following the circle of 5ths.
Moving on to Minor:
The Minor Tetrachord is the first 4 notes of the minor scale. Looking at it in terms of intervals: Whole Step, Half Step, Whole Step or WHW. Notice that the only difference between the Major and the Minor Tetrachord is the lower 3rd (the E became an Eb).
First, let’s combine these Minor Tetra Chords in the same manner as the majors ones above.
What do we get? A Dorian Scale – how handy!
C Minor Tetrachord + G Minor Tetrachord = C Dorian Scale
G Minor Tetrachord + D Minor Tetrachrod = G Dorian Scale
D Minor Tetrachord + A Minor Tetrachord = D Dorian Scale
In terms of whole steps and half steps we get: [W H W] W [W H W]
Now the real fun begins. Here’s what I discovered as I started teaching tetrachords:
Using just Major and Minor Tetrachords you can form all these common scales:
Dominant 7th (Mixolydian) Scale
Melodic Minor Scale
What about other common Tetrachords?
So, after all this, what’s the point? Sure it’s fun (for me at least) to look at all these different puzzle pieces and figure out how they all go together, but there’s a practical reason for all this too. It’s a proven fact that we learn better when we tackle things in smaller pieces. Every musician knows to practice small chunks of music and then gradually put the chunks together. Tetrachords, for me and many of my students, are a small piece that can be easily practiced with HUGE benefits when you put the pieces together.
Start by learning all of your Major and Minor Tetrachords in all 12 keys. Practice in a variety of orders, not just around the circle or chromatic. Then move on to the others.
Pick a Tetrachord to warm-up on and play it in all 12 keys very slowly as a longtone exercise.
Try improvising on just 1 tetrachord. Then start combining them together. Maybe you’ll come up with a sound you didn’t know you knew!