Recall the familiar C Major scale (right). Also recall the C Major triad consisting of three tones: C, E, and G. Now, let’s extend our knowledge of triads out to every note of the C Major scale. In other words, we’ll create a triad based on each note of the C Major scale.
This yields the chart below. Notice how each triad is correctly built upon a note of each tone in the scale and each consists of two thirds stacked on top of each other. For reference, the guitar chords are listed above each chords (except for vii, which we’ll leave alone for now; while it’s a legitimate chord, it’s best to save it for later). Also, be sure to realize that the guitar chords do not exactly correspond note-for-note to the triads. However, have a look at the tab below. You can finger the triads exactly as written. Try it out and notice how the two 3rd intervals are formed:

What do the Roman Numerals mean? Well, this is the traditional way to notate chords during harmonic analysis, which we’ll talk about in a future lesson. The great thing about this style of notation, which is not common in guitar music, is that it’s a convenient way to see how the chords are working together. Here’s how to interpret the Roman numeral symbols:
- Uppercase Roman Numerals: Indicated major triads. I, IV, and V are major triads. Major triads consist of the root, plus a major third above the root, and a minor third above the major third.
- Lowercase Roman Numerals: Indicates minor triads. ii, iii, vi are minor triads. Minor triads consist of the root, plus a minor third above the root, and a major third above the minor third.
- Lowercase Roman Numerals with a dot: Indicates diminished triads. vii° is a diminished triads. Diminished triads consist of the root, plus a minor third above the root, and a minor third above the first minor third.
- Uppercase Roman Numerals with a +: Indicates an augmented triad. There is no example in a natural scale tone triad. But, an example might be: “III+”. Augmented triads consist of the root, plus a major third above the root, and a major third above the first major third. These triads tend to be rare in guitar and popular music. A very popular example of hearing an augmented triad is in Wagner’s Overture to the third act of Die Walkure, aka “Ride of the Valkries”. You know, the music that famously appears in Apocalypse Now.
The best way to remember which triads of the scale tones are major is just to remember I-IV-V. Pronounced: “One-Four-Five”. The “One-Four-Five” chord progression is one of the most popular in popular music. Learn and don’t forget.
Things to Do:
1) Make sure you know these chords: D minor, E minor, F major (do not play the lower E and A strings as indicated in the graph above), G major, A minor. Here are the fingerings:
Remember, this is a theory lesson, so learning these chords in the context of playing the chords isn’t so important for this exercise. It’s important to learn these chords and how they relate to each other within the key of C Major. Look forward to more detail on this in future lessons.
2) As a sociological musical experiment, ask fellow guitarists the difference between an A major and an A minor chord. What is the typical answer that you get? You’re practically guaranteed that someone will describe the chord to you. Something like, “Oh, for a minor, you hold your hand a little different and put this finger here on the first fret.” The simple answer, for someone trained in music theory: “You just fret a C# for A Major and a C natural for A minor.”