Stack triads on every degree of a major scale and you get the seven chords that power most popular music.
Listen to this lesson
Synthesized voice, not a studio recording
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What you will learn
- How to derive the seven triads from any major scale.
- Why three of them are major, three are minor, and one is diminished.
- Roman numeral analysis and how to read a chord chart in any key.
- How tonic, subdominant, and dominant functions shape a progression.
The concept
Take any major scale and build a triad on top of each note, using only notes from that scale. In C major you get C, Dm, Em, F, G, Am, and B diminished. The pattern of qualities, major, minor, minor, major, major, minor, diminished, is identical in every major key.
We label these chords with Roman numerals to describe function instead of specific letters. I, ii, iii, IV, V, vi, vii diminished. Uppercase means major, lowercase means minor, the small circle marks the diminished chord. This is how a I IV V progression makes sense in any key without rewriting it.
Three of these chords carry most of the gravity in tonal music. I is home. V wants to fall to I. IV widens the space without leaving home. The other chords colour the journey between those poles.
On the guitar
Play the I IV V progression in G major using open chord shapes: G, C, D. Then play the same progression in D major: D, G, A. The shapes change but the function is identical.
Add the vi chord (Em in G, Bm in D) and you suddenly cover thousands of pop songs. The vi pulls toward a minor feel without leaving the key.
Exercises
- 01
Write out every chord of G, D, A, and E major using Roman numerals.
- 02
Play I vi IV V in three different keys without using a capo.
- 03
Take a song you know in C and transpose its chords to F by replacing each Roman numeral.
- 04
Identify which chord in a progression is the V. Listen for the strong pull home.
Common mistakes
- Mixing uppercase and lowercase Roman numerals. Capital is always major.
- Treating the diminished vii chord as a stranger. It is the V chord without its root.
- Memorising chord shapes for one key only and getting lost when a song is in another.
Listen, play, create
- Listen: Let It Be moves I V vi IV in C, an arrangement at the heart of pop.
- Play: loop a I IV V progression for two minutes and improvise the melody.
- Create: write a chorus using only I, IV, V, and vi.
Use these tools
Further reading
When you can name every chord by its number, you stop transposing in your head and start hearing structure instead of letters.