Lesson goals

• Understand what a triad is
• Build triads from any major scale
• Hear and see major, minor, diminished
• Label chords with Roman numerals and letters
• Create simple loops using diatonic triads

What is a triad

A triad uses three notes from the scale. Start on a degree, skip one, skip one again. That is 1, 3, 5.

Use only notes from the key you are in. If the key is C major, build each triad using only C, D, E, F, G, A, B.

3-Step Build Method

1. Pick the degree and write the key notes.
2. Stack 1-3-5 from that starting note (skip every other note).
3. Check chord quality by measuring the two stacked thirds.

Thirds and chord quality

Semitone = the smallest step in 12-tone music (one key to the very next key on piano, black or white).

Think of a triad as a third with another third stacked on top.

The Diatonic Pattern

In every major key, the triad quality order is always the same:

Diatonic means we only use notes that already belong to that key.

This pattern is for major keys. Minor-key harmony is introduced in a later lesson.

All seven triads in C major

All seven triads in G major

How to label chords

Practice

1. Write all seven triads in C major
2. Play I, IV, V back to back and listen to the movement
3. Switch to G major and rebuild all seven triads
4. Create a 4 chord loop using only diatonic triads
5. Try I-V-vi-IV in C major, then transpose that same degree pattern to G major

Focus on hearing the difference between major, minor, and diminished triads.

Quick review

• Triad formula: 1-3-5 from the scale.
• Quality pattern in major keys: I ii iii IV V vi vii°.
• Roman numerals: Uppercase major, lowercase minor, ° diminished.
• Workflow: Pick key, write scale, stack every other note.

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