Which interval structure correctly describes a minor triad?
AMajor third on the bottom, major third on top
BMinor third on the bottom, major third on top
CMajor third on the bottom, minor third on top
DMinor third on the bottom, minor third on top
A minor triad is built m3 + M3: a minor third (3 half steps) from root to the middle note, and a major third (4 half steps) from the middle note to the top. Example — D minor: D to F is a minor third, F to A is a major third. This is the exact reversal of a major triad (M3 + m3). Both triads use the same two intervals; only the order changes. Recognizing this symmetry is the core insight: same ingredients, opposite arrangement, opposite color.
Question 2 Multiple Choice
You build a chord by stacking two minor thirds starting from C: C–E♭–G♭. What type of triad is this?
AMinor triad — two minor thirds produce a minor chord
BDiminished triad — two stacked minor thirds produce a diminished fifth from root to top
CAugmented triad — the flatted notes create an augmented quality
DMajor triad — minor thirds combine to produce a major sound at the outer interval
Two stacked minor thirds (3 + 3 = 6 half steps) produce a diminished fifth — the tritone — from root to top note. C–E♭ is a minor third; E♭–G♭ is another minor third; C to G♭ is only 6 half steps, a diminished fifth. This is the diminished triad (m3 + m3). Two minor thirds never produce a minor chord — a minor triad requires m3 + M3. The instability of the tritone at the outer interval is what gives diminished chords their tense, restless quality.
Question 3 True / False
A major triad and a minor triad contain the same two intervals (a major third and a minor third) — they just appear in opposite order.
TTrue
FFalse
Answer: True
This is the core insight of interval-stack triad construction. Major triad: M3 (bottom) + m3 (top). Minor triad: m3 (bottom) + M3 (top). Same two intervals, reversed order. The placement of the larger interval at the bottom vs. the top completely changes the chord's character from bright (major) to darker (minor). Understanding this reversal explains both triads from a single structural observation.
Question 4 True / False
An augmented triad has a larger outer interval (root to fifth) than a major triad.
TTrue
FFalse
Answer: True
An augmented triad is built M3 + M3: two major thirds stacked. This gives an augmented fifth (8 half steps) from root to top, compared to the perfect fifth (7 half steps) in a major triad. By contrast, a diminished triad (m3 + m3) has only a diminished fifth (6 half steps). The outer interval — perfect, augmented, or diminished — names the chord quality and follows directly from the stacked intervals.
Question 5 Short Answer
How would you construct a dominant seventh chord using the interval-stack method? Name each stacked interval and give a concrete example starting from G.
Think about your answer, then reveal below.
Model answer: A dominant seventh chord stacks three intervals: M3 + m3 + m3. Starting from G: G to B is a major third (4 half steps), B to D is a minor third (3 half steps), D to F is a minor third (3 half steps). Result: G–B–D–F, the G dominant seventh chord.
The interval-stack view extends directly from triads to seventh chords by adding one more third above. The dominant seventh begins with the major triad (M3 + m3) and adds a minor third on top. Rather than memorizing a separate formula for each chord type, you apply the same stacking logic: identify the quality of each successive third. This framework also extends to ninths, elevenths, and thirteenth chords (jazz extensions) by continuing to stack thirds above.