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What are the diatonic modes, and how does each one differ from major or minor?

Topic 8.1 Modes: identify and construct the seven diatonic modes by their characteristic altered scale degrees and their final.

A focused answer to AP Music Theory Topic 8.1, covering the seven diatonic modes (Ionian, Dorian, Phrygian, Lydian, Mixolydian, Aeolian, Locrian), how each is built on a different degree of the parent scale, the characteristic altered degrees that give each its color, and finding a mode by its final, with a worked construction.

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  1. What this topic is asking
  2. The seven modes
  3. Characteristic altered degrees
  4. Why modes are about pattern and final
  5. Constructing a mode
  6. Try this

What this topic is asking

The College Board (Topic 8.1) wants you to identify and construct the seven diatonic modes (Ionian, Dorian, Phrygian, Lydian, Mixolydian, Aeolian, Locrian) by their characteristic altered scale degrees and to find a mode from its final (the note that sounds like home).

The seven modes

On the white keys, the modes run C (Ionian), D (Dorian), E (Phrygian), F (Lydian), G (Mixolydian), A (Aeolian) and B (Locrian). Each shares the same seven pitches but places its half steps in a different position relative to its final, which gives each mode its own color.

Characteristic altered degrees

The fastest way to identify a mode is to decide whether it sounds major or minor, then find the one altered degree (or two, for Locrian) that distinguishes it from the plain scale.

Why modes are about pattern and final

The central idea is that, like major and minor, a mode is a pattern of intervals around a final, not a fixed set of pitches. The same white-key collection yields seven different modes purely by changing which note is the final, because that moves the half steps to different positions relative to home. This is why the characteristic degree matters so much: it is the single altered note that tells your ear which mode you are in. To identify a mode in a piece, find the note that feels like home (the final, often where phrases rest), spell the scale from there, and compare it with major or minor to locate the characteristic alteration. To construct a mode, either start the parent scale on the right degree or take a major or minor scale and apply the one characteristic change. Hearing and naming modes by final and characteristic degree is the modal counterpart of the scale-degree thinking that runs through the whole course.

Constructing a mode

To construct a mode, either write the parent major scale and begin on the degree that matches the mode (Dorian on degree 2, Mixolydian on degree 5, and so on), or take a major or minor scale on the desired final and apply the characteristic alteration.

Try this

Q1. Which mode is the natural minor scale, and on which white-key note does it start? [1 point]

  • Cue. Aeolian; it runs A to A on the white keys.

Q2. What is the characteristic altered degree of the Lydian mode? [2 points]

  • Cue. A raised fourth degree; Lydian is like a major scale but with degree 4 raised a half step.

Exam-style practice questions

Practice questions written in the style of College Board exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.

AP 2021 (style)1 marksSection I (multiple choice, written). Which mode is a major scale with a lowered seventh degree? (A) Dorian (B) Phrygian (C) Mixolydian (D) Lydian
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The correct answer is (C) Mixolydian.

Mixolydian is like a major (Ionian) scale but with the seventh degree lowered a half step, giving a flat seventh. This lowered leading tone produces its characteristic, slightly bluesy or folk-like sound (for example G to G on white keys: G, A, B, C, D, E, F, G, with F natural as the lowered seventh).

(A) Dorian is a minor scale with a raised sixth. (B) Phrygian is a minor scale with a lowered second. (D) Lydian is a major scale with a raised fourth. The trap is confusing Mixolydian (lowered 7, major-based) with Lydian (raised 4); both are major-based modes but differ in the altered degree.

AP 2023 (style)2 marksSection II (free response, notation). Notate one octave of the D Dorian scale ascending and identify the characteristic altered degree compared with the natural minor scale.
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A 2-point construction question.

(1 point) D Dorian uses the white keys from D to D: D, E, F, G, A, B, C, D (the same notes as C major but starting on D).
(1 point) Compared with D natural minor (which has B flat), D Dorian has a raised sixth degree, B natural; the raised sixth is the characteristic tone that distinguishes Dorian from natural minor.

Markers reward the correct white-key spelling D to D and identifying the raised sixth (B natural) as the characteristic Dorian degree.

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