Triads and the I, IV and V chords
A triad is three notes stacked a skip apart, drawn all on lines or all in spaces. The I, IV and V chords are the triads on the first, fourth and fifth notes of a key (in C major: C E G, F A C and G B D), and they harmonise a great many simple tunes.
A triad is three notes stacked a skip apart: a root, the note a third above it, and the note a fifth above it. Written in root position, all three sit on lines or all three in spaces, stacked like a snowman. The I, IV and V chords are the triads built on the first, fourth and fifth notes of a key. In C major they are C E G, F A C and G B D, and between them they harmonise a great many simple tunes.
Reading a triad
Don't read a triad as three separate notes. Read the bottom note and the shape:
- Line, line, line (or space, space, space) stacked tight together is a root-position triad.
- The bottom note is the root, and it names the chord: a snowman whose bottom sits on middle C's ledger line is C major.
- In the right hand's five-finger position, a root-position triad is always fingers 1, 3 and 5.
I, IV and V in three keys
The Roman numerals count up the scale from the key note. I is the chord on the first note, IV on the fourth, V on the fifth.
| Key | I | IV | V |
|---|---|---|---|
| C major | C E G | F A C | G B D |
| G major | G B D | C E G | D F♯ A |
| F major | F A C | B♭ D F | C E G |
Notice that one chord turns up in all three keys under different numbers: C E G is I in C, IV in G and V in F. The key decides the number; the notes stay the same.
Easy shapes for the left hand
Jumping the whole hand from root to root is hard at first. Instead, keep the left hand in one place and change as few notes as possible. These shapes, taught in many method books, keep the little finger near C:
| Chord | Notes, low to high | Fingers |
|---|---|---|
| C (I) | C E G | 5 3 1 |
| F (IV) | C F A | 5 2 1 |
| G7 (V7) | B F G | 5 2 1 |
The G7 shape adds F, the seventh of the chord, and leaves out D. It is the version of V that most beginner books teach, because it moves only one or two fingers from C.
Why I, IV and V matter
In a major key, the I chord feels like home, the V chord pulls back towards home, and the IV chord moves away. Many folk songs, hymns and children's songs can be harmonised with these three alone: Twinkle, Twinkle, Little Star, Ode to Joy and Lightly Row among them.
Common mistakes
- Reading chord notes one by one. Read the bottom note and the shape.
- Landing the notes unevenly. A chord's notes should sound together. Place the hand, then press all three at once, like a stamp.
- Forgetting the key signature. The V chord of G major is D F♯ A, not D F A.
- Moving the hand for every chord. Use the nearest shape, and let only the fingers that must move, move.
How to practise
- Play C E G, F A C and G B D in the right hand, fingers 1 3 5, reading them from the staff.
- Play I IV V I in C with the left-hand shapes above: C E G, C F A, B F G, C E G.
- Put a tune on top. Play the tune of Twinkle, Twinkle in the right hand and change the left-hand chord when the harmony changes.
- Move to G and F major. Use the same patterns with the key's sharp or flat.
How Octotune helps
Unit 11 of Octotune's adult path is chords: a concept card ("a triad is a snowman"), chord cards on C, F and G, then pages of I, IV and V with the chords in the right hand and the root in the left, a Triads lesson, and three songs with left-hand chords (Twinkle, Ode to Joy and Lightly Row), before I, IV and V in G and F. Every chord is answered by playing all three notes. Open Octotune.
Next: Sight-reading.
Questions
What is a triad?
Three notes stacked a skip apart: a root, the third above it and the fifth above it. In root position all three sit on lines or all three in spaces, like a snowman.
What are the I, IV and V chords in C major?
C major (C E G), F major (F A C) and G major (G B D): the chords built on the first, fourth and fifth notes of the C major scale.
What are I, IV and V in G major and F major?
In G major: G B D, C E G and D F sharp A. In F major: F A C, B flat D F and C E G.
How should a beginner play I, IV and V in the left hand?
Without moving the hand: C as C E G, F as C F A, and G7 as B F G. Each shape keeps the little finger near C and changes as few notes as possible.