Major and Minor Thirds - Seeing a Major Scale Afresh

Guitar Lesson


In this guitar lesson I will show you how third intervals are laid out in a Major Scale which will have you seeing scales from a new perspective.
Guitar Lesson Objectives:
  1. ​Understand how to harmonize a Major Scale by third intervals
  2. Recognize which degrees/notes of the Major Scale correspond to major or minor thirds if we harmonize the scale in thirds
  3. Play major and minor third intervals in various positions
  4. Learn how to apply thirds in musically meaningful phrases
Ok, got it - just take me to the exercises for this lesson!

There are few topics more useful to expanding one's musical ability than intervals. By studying intervals and visualizing them on the fretboard, you will expand your phrasing/melodic skills as well as your harmony (chords) skills since major and minor thirds are central to a lot of chord types (such as minor and major chords as you can guess!).

In this guitar lesson I will show you several exercises that will get you thinking about third intervals and which will also have you looking at scales with a fresh set of eyes. We won't go too deep into theory, but have a look at the theory section below if you need to freshen up on the idea behind third intervals.

A third interval, for the purposes of this guitar lesson is the space between three consecutive notes of a Major Scale. So if we consider a G Major Scale, which has the notes G, A, B, C, D, E, F#, we can start from G, and the third note up from G is B. In this case we have 2 whole steps, which means G to B is a Major Third Interval. So remember: Major Third = 2 Whole Steps.

If we continue to the next note in the G Major Scale - A - we see the third note from A is C, which is a one and a half step interval. This is a minor third: Minor Third = 1 and a Half Steps.

We could continue this way for each note and we would see that for every note in the Major Scale, there is a corresponding third interval that we can build from the given scale note- either major or minor third. We can see this on a staff as below:

Major Scale in Thirds 

Above is not to be confused with harmonizing a Major Scale in triads (see my Triads Guitar Lesson if you are interested in harmonizing the Major Scale as triads). Where you see a letter without lowercase 'm', that means a Major Third, not Major Triad. Where you see a lowercase 'm', I am referring to a Minor Third, not a Minor Triad.

This means that for any given Major Scale, we can form either a major or minor triad. Specifically, we have the following:

Major Scale DegreeThird Interval Type
1Major Third
2Minor Third
3Minor Third
4Major Third
5Major Third
6Minor Third
7Minor Third

That is all the theory we need to appreciate what is happening in this guitar lesson. In the exercises I will show you how to visualize third intervals on the fretboard which will go a long way in expanding your fretboard knowledge as well as your ability to navigate through scales in a new light.

Exercises in this Intervals Guitar Lesson

Major Scale Harmonized in Thirds


In this exercise we will take a look at a Major Scale and see how we can play the scale in third intervals, which might give you a new perspective on scales!