← Back to the Music Theory I outline The Course Maker
← Music Theory I outline
Week 10 · Lecture outline

Week 10 — Lecture Outline · Seventh Chords

Music Theory I · MUS 156 Fictional sample

Course: MUS 156 Music Theory I · Kenosis College
Instructor: Professor Hemsworth
Unit: Learning Unit 10 of 16 (Week 10) · two sessions per week
Objectives: SLO 4 (spell and identify seventh chords in every quality and inversion, from notation and from chord symbols) · SLO 7 (translate what you hear into names and notation — the spine) · SLO 8, next component (read a chart's seventh-chord symbols the way working musicians do — and The Chart launches)
Sessions: session 1 — teach · session 2 — studio

You already hear this. We're going to name what you already know.

Sung in Aural Skills I: arpeggiated sevenths — MUS-155 sings the four-note stacks you spell here this morning: root, third, fifth, seventh, up and down, quality by quality, so the sound and the spelling land on the same day.

Week at a Glance

The table below summarizes the unit in one screen.
The unit's big question "Cmaj7 and C7 differ by one note — and your ear has never once confused them. What is that note doing, and how do you read, spell, and call all five seventh-chord qualities the way charts actually name them?"
By the end of the unit, students can… (1) build any seventh chord as a triad plus one more third — four notes deep; (2) spell all five qualities on any root: major seventh, dominant seventh, minor seventh, half-diminished, fully diminished; (3) read and write the chart symbols — Cmaj7, C7, Cm7, Cm7♭5, C°7 — and know that a plain 7 always means the dominant recipe; (4) harmonize a major scale in diatonic sevenths and prove the chord on ^7 is viiø7, half-diminished, never fully diminished; (5) name all three inversions with the figures 7 · 6/5 · 4/3 · 4/2; (6) read slash chords: the letter after the slash is the bass note you actually hear.
Key vocabulary seventh chord, chordal seventh, major seventh chord (MM7), dominant seventh chord (Mm7), minor seventh chord (mm7), half-diminished seventh chord (ø7), fully diminished seventh chord (°7), diatonic sevenths, viiø7, third inversion, figures 7 / 6/5 / 4/3 / 4/2, chord symbol, slash chord
Materials Deck 10 · the Week 10 chapter · paper keyboards from Week 1 · relay cards and quality-vote paddles (or just hands) for the studio · a piano or keyboard in the room · students' own instruments welcome
Timing note 7 segments ≈ 150 min. Session 1 = Segments 1–6 (75). Session 2 = Segment 7 (75: studio). Scale to your own pacing.

Segment 1 — Ear first: two chords, one note apart (8 min) · Session 1 opens

Hook (no notation on screen yet). Play Cmaj7, let it shimmer. Then play C7, same voicing, one note dropped a half step. Ask: "Same chord?" Every head shakes no. Ask for adjectives — you'll get dreamy, floaty, jazzy for the first and bluesy, restless, wants-to-go-somewhere for the second. Play them again. The room has just distinguished a major seventh chord from a dominant seventh chord with total confidence and zero vocabulary.

  • "One note. The two chords differ by ONE note, and your ear has never once confused them. Today you find out what that note is, and by the end of the week you'll spell all five flavors of it on any root, on demand."
  • The promise (say it, then put it on the board): "By the end of this week you can read Cmaj7, C7, Cm7, Cm7♭5, and C°7 off a chart correctly the first time — and spell each one, four notes deep, on any root."
  • The Chart launches this week. Say it early and warmly: the term project — a full lead sheet of a song they love, transcribed by ear, analyzed, transposed, performed — starts inside this week's assignment with milestone 1: choose your song. The chord symbols they learn this morning are the exact notation their Chart will be written in.

Memory hook: "A seventh chord is a triad that kept stacking — one more third, one more story on the house."

Segment 2 — The recipe: one more third (10 min)

Plain language first. Unit 9 built triads: root, third, fifth — stacked thirds. Keep going. Add one more third on top of the fifth and the new note sits a seventh above the root: a seventh chord. Four notes deep. On a staff, a triad is three stacked circles; a seventh chord is four — the snowman gets a hat.

  • The new note is called the chordal seventh (or just "the seventh"). Everything new this week lives in that one note: what kind of seventh it is (major, minor, or diminished above the root) combines with the triad underneath to make the chord's quality.
  • Worked example (walk it at the piano): C4–E4–G4, the C major triad from unit 9. Stack one more third: B4. Now the outer interval C4→B4 is a major seventh — the leaning, almost-an-octave sound from unit 6. Play the stack: that's the shimmer from the hook.
  • Interaction (2 min): "Triad or seventh chord?" — play five chords, the room holds up three fingers or four. Their ears count better than they expect.

Misconception + cure:

  • ❌ "Any four notes make a seventh chord — just add whatever sounds thick."
    ✅ Cure: same law as unit 9: thirds. A seventh chord is stacked thirds, four deep — root, third, fifth, seventh. C–E–G–A is thick, but the A is a sixth, not a seventh, and the chord has a different name and a different job. The stacking law is what makes chords spellable.

Segment 3 — The five qualities (14 min)

Ear first, then the table. Play all five on C, slowly, naming adjectives before names: shimmer … blues engine … velvet … suspense … horror-movie doorknob. Then build the table on the board, one row at a time:

Quality Recipe On C Typed symbol
Major seventh (MM7) major triad + major seventh C E G B Cmaj7
Dominant seventh (Mm7) major triad + minor seventh C E G B♭ C7
Minor seventh (mm7) minor triad + minor seventh C E♭ G B♭ Cm7
Half-diminished (ø7) diminished triad + minor seventh C E♭ G♭ B♭ Cm7b5
Fully diminished (°7) diminished triad + diminished seventh C E♭ G♭ B𝄫 Cdim7 
METER: free    CLEF: treble
| <C4,E4,G4,B4>/w <C4,E4,G4,Bb4>/w <C4,Eb4,G4,Bb4>/w <C4,Eb4,Gb4,Bb4>/w <C4,Eb4,Gb4,Bbb4>/w |

Five whole-note stacks on the treble staff, all rooted on C4: first C–E–G–B (major seventh chord), then C–E–G–B♭ (dominant seventh), C–E♭–G–B♭ (minor seventh), C–E♭–G♭–B♭ (half-diminished), and C–E♭–G♭–B𝄫 (fully diminished). Each stack changes exactly one note from its neighbor — five qualities, one staircase down.

  • Play the fence left to right: one note changes at each step. Have the room sing the note that moved. This is the whole quality system heard as a staircase.
  • The bottom two rows deserve two extra minutes. Both sit on a diminished triad (C–E♭–G♭). The difference is the seventh: half-diminished keeps a minor seventh (B♭ — only half the chord is diminished); fully diminished squeezes the seventh down to a diminished seventh (B𝄫 — everything diminished, top to bottom). B𝄫 is not a typo and not "really an A": unit 1's spelling law still governs. Same key on the piano, different written note, different chord.

Misconception + cure:

  • ❌ "ø and ° are just two fonts for the same symbol."
    ✅ Cure: two different chords. Cm7♭5 (ø7) = C E♭ G♭ B♭; C°7 = C E♭ G♭ B𝄫. One note apart, and your ear can hear the difference — the fully diminished chord is noticeably darker and tenser. Say "half-diminished" and a keys player knows exactly which chord you mean; blur the symbols and you'll get the wrong one.

Segment 4 — The symbols: what "7" really means (12 min)

Plain language first. Chord symbols are the working musician's alphabet — every lead sheet, worship slide, and jam-session text message uses them. The system this course types: Cmaj7, C7, Cm7, Cm7b5, Cdim7, and the slash chords coming in Segment 6. One reading rule saves years of confusion:

  • A plain 7 means the dominant recipe. C7 = major triad + minor seventh (C E G B♭). It never means "C major with a major seventh."
  • maj7 is the symbol that means the major seventh. Cmaj7 = C E G B. The symbol spells out "maj" precisely because the plain 7 was already taken.
  • Cm7 = minor triad + minor seventh. Cm7b5 = m7 with the fifth flattened — which is exactly the half-diminished recipe, and why players call it "m7 flat 5." Cdim7 = fully diminished.
  • Worked example, at the board: a chart says G7. Recipe: G major triad (G–B–D) + minor seventh above G (F). G B D F. Then Gmaj7: G–B–D + major seventh (F♯). G B D F♯. One accidental apart; two different chords; the chart told you which with three characters.
  • Interaction (3 min): flash symbols, the room calls the recipe before the notes: "Am7?" → "minor triad plus minor seventh." "E7?" → "major triad plus minor seventh." Then spell two of them out loud together (A C E G · E G♯ B D).

Misconception + cure:

  • ❌ "7 means major seventh — it's the plain, default one."
    ✅ Cure: history went the other way: the plain 7 was claimed by the dominant sound centuries of ears heard as the seventh chord. On a chart, C7 and Cmaj7 are one accidental and a whole genre apart — play B natural on a blues gig where the chart says C7 and everyone will turn around. The studio's first round exists to weld this into your hands.

Segment 5 — Diatonic sevenths, and THE spelling everyone prints wrong (14 min)

Plain language first. Unit 9 harmonized the major scale in triads. Do it again, one story taller: build a seventh chord on every degree of C major, using only white keys — only notes the key supplies. The qualities fall out by themselves:

IM7 Cmaj7 · ii7 Dm7 · iii7 Em7 · IVM7 Fmaj7 · V7 G7 · vi7 Am7 · viiø7 Bm7♭5

  • Sing/point through the row at the piano. Two majors (I, IV), three minors (ii, iii, vi), one dominant — V7, the only one the key builds — and one half-diminished, on ^7.
  • Now the centerpiece. Build the ^7 chord slowly, at the board, out loud: B–D–F–A. B to D: minor third. B to F: diminished fifth. So far, the diminished triad from unit 9. B to A: minor seventh — count it: B up to A is a seventh's worth of letters, and ten half steps is the minor one. Diminished triad + minor seventh = half-diminished. viiø7.
  • Why can't it be fully diminished? Because viio7 on B needs A♭ — and A♭ is not in C major. Check any major key: the fully diminished seventh always demands a note the key signature doesn't own. viio7 is not diatonic to any major key. It has a real home — harmonic minor, where unit 11 will hand it its keys — but in a major key, the seventh chord on ^7 is viiø7. Always.
  • AI-critique moment (3 min, live on the projector). Paste into a chatbot: "In C major, spell the seventh chord built on B and name its quality. One sentence." Read it aloud. A large fraction of the time you'll get "B diminished seventh: B–D–F–A♭" — a chord containing a note that isn't in C major, delivered with total confidence. Have the room catch it: A♭ fails the key-membership test; the honest chord is B–D–F–A, half-diminished. "All term the tool drafts and you judge — and this week's tutorial audit runs on your own knowledge. This exact error is loose in the wild. Hunt it."

Misconception + cure:

  • ❌ "The chord on ^7 in major is viio7 — diminished triad, so diminished seventh."
    ✅ Cure: the triad is diminished; the seventh above the root is minor — the key has no other note to offer. Diminished triad + minor seventh = half-diminished, viiø7. The fully diminished version needs an accidental in every major key on the circle, which is exactly what "not diatonic" means. This is the most commonly printed wrong chord in amateur theory content — including, reliably, your chatbot's.

Segment 6 — Inversions, figures, and the slash (17 min) · Session 1 closes (~75)

Plain language first. Four notes means four candidates for the bass. Same chord, four floors — and unit 9's rule holds: inversion changes the color and the bass line, never the chord's identity.

  • The figures, on the board — slashes, never hyphens: root position 7 · third in the bass 6/5 · fifth in the bass 4/3 · seventh in the bass 4/2. (Why slashes? Because a hyphen already has a job in figures — it marks a suspension, one number resolving to another over a single bass note, and that tool arrives in unit 14. Writing 6-5 when you mean 6/5 says something you don't mean. Keep the lanes clean now and unit 14 costs you nothing.)
  • Worked example — G7 up the floors, at the piano: G in the bass (7) · B in the bass (6/5) · D in the bass (4/3) · F in the bass (4/2). Play all four; have the room sing the bass note each time. Same chord every time — the ear confirms it.
METER: free    CLEF: treble
| <G3,B3,D4,F4>/w <B3,D4,F4,G4>/w <D4,F4,G4,B4>/w <F4,G4,B4,D5>/w |

Four whole-note stacks on the treble staff: the G7 chord in root position (G at the bottom), then first inversion (B in the bass — figure 6/5), second inversion (D in the bass — 4/3), and third inversion (F in the bass — 4/2). Four voicings, one chord.

  • Slash chords — the chart's way of ordering the bass. C/E reads "C chord, E in the bass": the letter after the slash is the bass note you actually hear. G7/D = G7 with D (the fifth) in the bass — which is the 4/3 idea wearing street clothes. Am7/G = A minor seven with its seventh in the bass: 4/2, on a worship slide. Figures are the classroom name; slashes are the gig name; one idea.
  • Interaction (3 min): flash C/E, G7/B, F/A, C7/Bb — the room calls the bass note and which chord member it is (third! third! third! seventh!).

Misconception + cure:

  • ❌ "C/E means C divided by E — some fraction thing — or a C and an E played together."
    ✅ Cure: read it as "C over E": the whole C chord, with E as the floor. The slash is a bass-note instruction, not arithmetic. Your bass player reads the right side; everyone else reads the left.

Why this makes you a better musician

This is the unit where charts stop bluffing you. The next lead sheet a music director hands you — Gmaj7, Em7, Am7, D7 — you read correctly the first time, because you know the plain 7 is a promise about the seventh, not a decoration. When the keys player asks what's in bar 12 and the honest answer is half-diminished, you can say "half-diminished" and be understood in two seconds instead of spelling four notes over the monitor mix. When a progression leans hard before the chorus, you can hear that it's the dominant seventh doing the leaning — the tritone from unit 7 is sitting inside V7, begging — and cue the band's landing instead of being surprised by it. And the slash chords that used to look like typos (C/E, G7/D) are now precise instructions you can hand your bass player. The studio drills all of it at gig speed; this week's assignment makes you fluent in both directions — and starts The Chart, where these exact symbols become your song, in your handwriting.

Callback + tease + hand-off.

  • Callback: "The hook was two chords, one note apart, and your ear never once confused them. Everything since has been giving that ear a spelling system four notes deep."
  • Tease: "Next unit — Roman numerals and function: the chords get jobs. Roman numerals go to work, progressions get named in real time, and viio7 finally collects the keys to its actual house."
  • Hand-off: read the chapter if you haven't; Tutorial 10 with your AI tutor is due before Week 10's second session — the studio builds straight on it. Practice set, quiz, discussion, and the Read-the-Chart assignment close the end of Week 10 — and inside that assignment, The Chart's milestone 1: choose your song. Come to the studio already thinking about which song is yours.

Segment 7 — Studio: "Cmaj7 vs. C7" (75 min) · Session 2

Run from the studio sheet (P-studio-week-10). Shape, for planning: ear-first quality votes (dreamy vs. bluesy, no names) → name-the-quality rounds on played sevenths → spelling relays on one root — teams build all five qualities on a single root at the board, one note per runner → the bass-note round: slash chords and inversions by ear and by figure. The studio is the payoff enacted: hear it, name it, spell it, call it across the room. 20 points, graded in session; the async make-up path (full credit) is on the studio sheet.

Instructor FAQ — common stumbles

The table below lists predictable Week 10 questions and quick cures.

Student says / does Quick cure
"So C7 is just short for Cmaj7, right?" Opposite chords of the week. Plain 7 = dominant recipe (minor seventh: C E G B♭); maj7 spells out "maj" because plain 7 was taken. Play both; the ear settles it in four seconds.
Writes B–D–F–A♭ for the seventh chord on ^7 in C major. Key-membership test: is A♭ in C major? No — so the chord can't be diatonic. The key offers A, making a minor seventh above B: half-diminished, viiø7. (This is also the week's chatbot trap — praise anyone who caught it in the wild.)
"Half-diminished and diminished 7 — same thing, different fonts?" Two chords, one note apart: ø7 keeps a minor seventh (Cm7♭5 = C E♭ G♭ B♭); °7 diminishes it (C°7 = C E♭ G♭ B𝄫). Play both; the °7 is audibly darker.
"B double-flat is just A. Why write it?" Same piano key, different written note — unit 1's law, still load-bearing. The °7 chord is stacked thirds: C–E♭–G♭–B𝄫 keeps the third-stack letters C-E-G-B. Write A and the stack breaks (C to A is a sixth).
Writes the figure as 6-5 or 4-2 with hyphens. Slashes: 6/5, 4/3, 4/2. The hyphen means a suspension (one number resolving to another over one bass) — that's unit 14's tool, and using it now says something you don't mean.
"Doesn't putting F in the bass make G7 a different chord?" Same four names, same chord, new floor. Inversion changes color and bass line, never identity — that's why the symbol stays G7 (G7/F if the chart wants that exact bass).
"Is C/E a fraction? C divided by E?" Read it "C over E": the C chord with E as the bass note. Left of the slash = the chord; right = the floor. It's an instruction to the bass player, not math.
"For my Chart song — does it have to be church music / jazz / something with fancy chords?" It has to be a song you love, can hum the bass of, and can legally listen to on repeat. Any genre. The coach in this week's assignment walks the suitability check with you — that's milestone 1.

Scope flag

This outline stays inside Week 10's fourteen ledger concepts (the seventh chord, the five qualities MM7/Mm7/mm7/ø7/°7, diatonic sevenths in major, third inversion, the figures 7 · 6/5 · 4/3 · 4/2, seventh-chord symbols, slash chords), drawing freely on unit 9's triads and inversions and units 6–7's interval machinery. The "viio7 lives in harmonic minor" remark is a forward-reference by name only — minor-key diatonic sevenths belong to unit 11 and are not taught or assessed here. "V7 leans toward home" is described as a sound (the unit-7 tritone inside it); Roman-numeral function vocabulary waits for unit 11. The suspension mention exists only to justify the slash-vs-hyphen convention; suspensions themselves are unit 14's. The minor-major seventh chord is deliberately absent here — unit 11 gives it a one-line color note when harmonic minor builds a seventh on its own tonic; it is never assessed in this course.

~ Professor Hemsworth's edition · Kenosis College · built with thecoursemaker.com