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Home›Music theory

Scales and keys

Build any major scale from one pattern of whole and half steps, name every scale degree, read a key signature at a glance, find your way around the circle of fifths, and tell a minor key from its relative major.

Progress

About this course

A piece in E major uses F♯, G♯, C♯ and D♯ in nearly every bar. Writing a sharp beside each of those notes would clutter the page, so composers gather them into a key signature at the start of every line. This course shows where that signature comes from. Every major scale is built from one pattern of whole and half steps, and starting the same pattern on G forces F to be raised to F♯ so that the sixth step stays a whole step.

The six units are the major scale, scale degrees, key signatures, the circle of fifths, minor scales, and relative and parallel keys. Three keys sit at the extremes: C major has nothing, C♯ major has all seven sharps, and C♭ major has all seven flats, giving 15 major key signatures in all. Each new sharp is the leading tone of the new key, while each new flat is the fourth degree of the new key. A perfect fifth is seven half steps, so twelve fifths are 12 × 7 = 84 half steps, exactly seven octaves, and on a piano the circle closes.

Minor scales come next. Compared with the major scale on the same tonic, natural minor lowers the 3rd, 6th and 7th: C major is C D E F G A B and C natural minor is C D E♭ F G A♭ B♭. In movable-do solfège the lowered notes get their own syllables, me, le and te. The last unit uses a circle in 3D to jump from an outer major key to its relative minor on the inner ring, where the key signature stays the same and only the tonic and the scale change.

Before you start

Whole steps, half steps and note letters appear throughout these lessons. Familiarity with them helps you check why a scale needs a sharp or flat. Intervals covers those distances; here you use them to build scales, read key signatures and compare keys.

When you finish

You can build a major scale from its whole and half steps, name scale degrees, and read the sharps or flats in a key signature. You can follow the circle of fifths, compare forms of the minor scale, and distinguish relative keys that share a signature from parallel keys that share a tonic.

  1. 1The major scaleEvery major scale follows the same steps, W-W-H-W-W-W-H, so a scale that starts on G is forced to use one black key, F♯.
  2. 2Scale degreesThe seventh note of a major scale sits a half step below the tonic, which is why it is called the leading tone: the ear expects it to rise.
  3. 3Key signaturesUp to seven sharps can sit at the start of a staff, and they always appear in the same order: F, C, G, D, A, E, B.
  4. 4The circle of fifthsGo up a perfect fifth twelve times from C and you land on C again, seven octaves higher, having passed through every major key on the way.
  5. 5Minor scalesA minor uses the same seven white keys as C major, but starting on A turns the second step into a half step and lowers the third.
  6. 6Relative and parallel keysC major and A minor share a key signature with no sharps or flats; C major and C minor share a tonic but are three flats apart.

Related courses

  • Reading notes
    Learn to read pitches on the staff: treble clef, bass clef, ledger lines, the grand staff, sharps and flats, and the different names musicians use for the same notes. Every unit has a staff quiz or a keyboard you can play.
  • Rhythm and meter
    How music is measured in time: the beat and tempo, note values and rests, dots and ties, simple meters like 3/4 and 4/4, compound meters like 6/8, and syncopation, triplets and pickups. Every unit has the rhythm lab with a tap-along test that scores each tap in milliseconds, and most units add a metronome for any time signature and note blocks you stack into bars.
  • Intervals
    An interval is the distance between two notes. Count half steps on the keyboard, name thirds, fourths, fifths and octaves, hear why some intervals sound stable, and train your ear and voice with melodies everyone knows.
  • Chords
    Stack thirds to build triads, hear the difference between major, minor, diminished and augmented, name every chord in a key with Roman numerals, read inversions and seventh chords, and follow the progressions and cadences that end a musical phrase.
Sources for this course (5)
  • Open Music Theory 2e (Viva Pressbooks; ideas only, no sentences copied): "Major Scales, Scale Degrees, and Key Signatures" (W-W-H-W-W-W-H, scale named for first note incl. accidental, scale-degree numbers with carets, do re mi fa sol la ti, tonic/supertonic/mediant/subdominant/dominant/submediant/leading tone and how the names were derived, clef-key-time order, order of sharps F C G D A E B and flats B E A D G C F, last sharp a half step below the tonic, second-to-last flat is the tonic, C and F memorised, C♭ seven flats and C♯ seven sharps, circle of fifths with enharmonic keys at 5, 6 and 7 o'clock; viva.pressbooks.pub/openmusictheory/chapter/major-scales/) and "Minor Scales, Scale Degrees, and Key Signatures" (natural W-H-W-W-H-W-W, harmonic W-H-W-W-H-3H-H, melodic up W-H-W-W-W-W-H and down = natural, lowered 3 6 7 / 3 6 / 3, me le te, subtonic, parallel and relative, relative minor three half steps below, D♭ major and B♭ minor not A♯ minor, three flavours of the same key, first and last notes and the Louise Reichardt song in F minor; viva.pressbooks.pub/openmusictheory/chapter/minor-scales/)
  • musictheory.net lessons 21-24 used as a cross-check only. Wikipedia "Circle of fifths" (Diletskii Grammatika 1677, Heinichen Musicalischer Circul 1711 and 1728, relative minor placed beside its major; en.wikipedia.org/wiki/Circle_of_fifths) and C. R. Jensen, "A Theoretical Work of Late Seventeenth-Century Muscovy: Nikolai Diletskii's Grammatika and the Earliest Circle of Fifths", JAMS 45/2 (1992)
  • abstract (surviving variants Smolensk 1677, Moscow 1679 and 1681; doi.org/10.2307/831450)
  • Wikipedia "The Well-Tempered Clavier" (Book 1 autograph dated 1722, 24 keys, C major then C minor then up by half steps; en.wikipedia.org/wiki/The_Well-Tempered_Clavier)
  • Wikipedia "Solfège" and "Guido of Arezzo" (ut re mi fa sol la from Ut queant laxis, 11th century, ut became do in 17th-century Italy, si added later, ti from Sarah Glover in the 19th century, fixed do in Romance-language countries; en.wikipedia.org/wiki/Solf%C3%A8ge).

Checked: 2026-10-17