AP Music Theory Unit 2 Cheat Sheet

The basics

What it covers: Minor scales in all three forms, how keys relate to one another, other scales (chromatic, whole-tone, pentatonic), intervals by size and quality, transposing instruments, and timbre, melody, and texture.

Exam weight: AP Music Theory is weighted by section, not by unit (45% multiple choice, 45% free response, 10% sight-singing). Unit 2's minor scales and intervals underlie the harmony units that follow.

The big question: How do minor keys, intervals, and texture expand the fundamentals into the tools you need to analyze real music?

Big Ideas covered: Pitch (BI 1), Rhythm (BI 2), Music Design (BI 4).

The key terms you must know

• Natural / harmonic / melodic minor — the three forms of minor; they differ only in the 6th and 7th degrees.
• Relative keys — a major and minor key that share a key signature (a minor 3rd apart).
• Parallel keys — a major and minor key that share a tonic (e.g., C major / C minor).
• Closely related keys — keys whose signatures differ by no more than one accidental.
• Chromatic / whole-tone / pentatonic — scales of all half steps, all whole steps, and five notes.
• Interval size vs. quality — letter-name distance vs. exact half-step content.
• Perfect interval — the quality of unisons, 4ths, 5ths, and octaves.
• Interval inversion — flipping an interval; sizes sum to 9 and quality reverses.
• Compound interval — an interval larger than an octave (e.g., a 9th).
• Transposing instrument — one whose written pitch differs from concert (sounding) pitch.
• Timbre — tone color; why instruments sound different on the same pitch.
• Monophony / homophony / polyphony — one line; melody + accompaniment; multiple independent lines.

Key themes to remember

• Minor is just major with altered degrees. Every minor form shares its key signature with a relative major; only 6 and 7 change.
• Keys are a web of relationships. Relative, parallel, and closely related keys share pitches — the basis of modulation later.
• Name intervals in two steps. First count letter names (size), then count half steps (quality). Never skip a step.
• Inversion is symmetrical. Sizes always sum to 9 and qualities flip — a fast way to check your work.
• Sound has three descriptors. Timbre (color), melody (contour/motion), and texture (how many lines) describe how music actually sounds.

Common exam traps

• Don't forget to raise 7 in harmonic minor. The raised leading tone is an accidental, not part of the key signature — write it in.
• Melodic minor changes on the way down. Ascending raises 6 and 7; descending it's plain natural minor again.
• Relative ≠ parallel. Relative keys share a signature (different tonic); parallel keys share a tonic (different signature). Don't swap them.
• Only 1, 4, 5, 8 can be "perfect." A 3rd or 6th is major/minor, never perfect — a classic interval-quality trap.
• Count size by letter names, not half steps. C to E is a 3rd (C-D-E = three letters) even though it's 4 half steps.
• Transposing instruments sound different than written. If asked for concert pitch, transpose — don't just read the written note.