AP Music Theory connects written notation, sound, harmony, and musical form. This cheat sheet helps students review the core tools needed for analysis, sight singing, dictation, and part writing. It is especially useful for checking chord spelling, Roman numerals, cadences, and voice-leading rules while practicing exam-style problems.
The most important ideas are key signatures, scale degrees, intervals, chord quality, harmonic function, and smooth voice leading. Diatonic triads and seventh chords are labeled with Roman numerals based on their scale degree and quality. Figured bass shows inversion, while cadences and phrase structure explain how harmony creates musical direction and closure.
Key Facts
- Major scale pattern is W W H W W W H, where W means whole step and H means half step.
- Natural minor scale pattern is W H W W H W W, harmonic minor raises scale degree 7, and melodic minor raises scale degrees 6 and 7 when ascending.
- In major keys, diatonic triads are I major, ii minor, iii minor, IV major, V major, vi minor, and vii diminished.
- In minor keys, common harmonic minor triads are i minor, ii diminished, III augmented or major in context, iv minor, V major, VI major, and vii diminished.
- Triad inversions are root position with no figure or 5/3, first inversion with 6, and second inversion with 6/4.
- Seventh chord inversions are root position 7, first inversion 6/5, second inversion 4/3, and third inversion 4/2.
- A dominant seventh chord is built as 1 3 5 b7 above the root, and in major keys V7 contains scale degrees 5, 7, 2, and 4.
- Basic part-writing rule: resolve tendency tones by moving scale degree 7 up to 1 and chordal sevenths down by step.
Vocabulary
- Scale Degree
- A numbered note of a scale, such as 1 for tonic, 5 for dominant, and 7 for leading tone.
- Roman Numeral Analysis
- A system that labels chords by their scale degree, quality, and inversion within a key.
- Figured Bass
- A shorthand notation using numbers below a bass note to show intervals above the bass and chord inversion.
- Cadence
- A harmonic ending or pause that gives a phrase a sense of arrival, continuation, or closure.
- Tendency Tone
- A note that strongly wants to resolve in a specific direction, such as the leading tone moving up to tonic.
- Voice Leading
- The way individual melodic lines move from one chord to the next in a harmonic progression.
Common Mistakes to Avoid
- Confusing chord quality with Roman numeral case is wrong because uppercase numerals show major or augmented chords, while lowercase numerals show minor or diminished chords.
- Forgetting inversion figures is wrong because a chord with the same notes can have a different bass note, which changes labels such as I, I6, and I6/4.
- Doubling the leading tone in four-part writing is wrong because scale degree 7 has a strong pull to tonic and doubling it often creates awkward or parallel motion.
- Resolving a chordal seventh upward is wrong because the seventh of a seventh chord normally resolves down by step.
- Labeling every V to I motion as a perfect authentic cadence is wrong because a PAC requires root-position V to root-position I, with scale degree 1 in the soprano on the final chord.
Practice Questions
- 1 In the key of G major, spell the V7 chord and name its chord tones by scale degree.
- 2 In the key of D minor, identify the Roman numeral and inversion for the notes F, A, D with F in the bass.
- 3 Write the quality of each diatonic triad in C major: I, ii, iii, IV, V, vi, and vii.
- 4 Explain why resolving the leading tone correctly is important in tonal harmony and part writing.