Questions: Building Triads from Scale Degrees

Question 1

What type of triad is built on scale degree 2 (D) of C major, and how do you determine this without memorizing a chart?

• A. Major — the second scale degree always produces a major triad
• B. Minor — counting semitones gives D to F (3 semitones) then F to A (4 semitones), a minor triad
• C. Diminished — the second scale degree is adjacent to the leading tone
• D. Augmented — the raised fourth gives the third an extra semitone

Answer: (B)

To identify the triad on D in C major, take the diatonic notes D–F–A. Count semitones: D to F is 3 semitones (minor third), F to A is 4 semitones (major third). Minor third stacked below major third = minor triad. The skill is derivation from interval counting, not memorization. This is the ii chord of C major — always minor in any major key, for the same structural reason.

Question 2

In natural minor, the chord built on scale degree 5 is minor rather than major. Why does this matter for harmony?

• A. It doesn't matter — the fifth scale degree sounds the same regardless of chord quality
• B. A minor v chord lacks the leading tone, weakening the dominant-to-tonic resolution that defines functional harmony
• C. A minor v chord is easier to play on instruments, which is why natural minor is preferred
• D. The fifth scale degree must be major by definition — natural minor raises it automatically

Answer: (B)

Functional harmony depends on the leading tone — the note a half step below the tonic — creating strong upward pull into the tonic. In natural minor, scale degree 7 is a whole step below the tonic (the subtonic), not a half step. The natural v chord contains no leading tone and produces a much weaker dominant-to-tonic pull. When composers want a strong authentic cadence in a minor key, they raise scale degree 7, creating harmonic minor and a major V chord. This is why harmonic minor exists.

Question 3

In a major key, the triad built on scale degree 7 (the leading tone) is diminished.

• T. True
• F. False

Answer: True

Build the triad on B in C major: B–D–F. B to D is a minor third (3 semitones), D to F is a minor third (3 semitones). Two stacked minor thirds = diminished triad. This holds in every major key because the seventh scale degree's position — one semitone below the tonic — means the intervals above it always stack two minor thirds. No memorization required; the interval structure of the major scale forces this result.

Question 4

Most diatonic triad in a major key is either major or minor.

• T. True
• F. False

Answer: False

The triad built on scale degree 7 (the leading tone) is diminished — neither major nor minor. A diminished triad consists of two stacked minor thirds, producing a tritone between root and fifth rather than a perfect fifth. In C major, B–D–F is the diminished triad (vii°). This matters in practice: the vii° chord functions differently from major and minor triads and is typically treated as an incomplete dominant seventh chord.

Question 5

Describe the process for determining the quality of any diatonic triad without referring to a memorized chart.

Model answer: Identify the root (the scale degree), take the note a third above it in the scale (skip one scale degree), then take the note a fifth above the root (skip another). Count the semitones from root to third, and from third to fifth. If the lower interval is 4 semitones (major third) and the upper is 3 (minor third), the triad is major. If 3 then 4, it is minor. If 3 then 3, it is diminished. The quality is a direct consequence of the scale's interval pattern, not something to memorize separately.

This derivation approach is both more durable and deeper than memorization: understanding why vii° is always diminished in major keys connects to the structure of the major scale itself. A student who can derive triad quality from interval counting will never confuse major-key and minor-key triad patterns, because they understand the underlying mechanism.