Music theory: free course in 80 lessons
Music theory is not a rulebook: it is the user's manual for what you hear. It explains why a melody "lands" where it should, why a chord sounds sad or bright, and how to read in seconds what a composer wrote three centuries ago.
This course starts from scratch — the names of the piano keys — and takes you step by step all the way to modes, rare scales, jazz harmony and the analysis of great works. Every lesson combines a clear explanation, examples to listen to and to play on the keyboard, a short quiz and links to the site's interactive exercises.
How to use it? Follow the chapters in order if you are a beginner; otherwise use the level shown on each lesson (1 = discovery, 6 = expert) to pick what you need. Read with a keyboard within reach: theory only truly makes sense through your fingers and your ears.
Notes and the staff
- The keyboard and note names
- The staff and the treble clef
- The bass clef and the grand staff
- Ledger lines and ottava
- Octaves and registers: C4 or Do3?
- Accidentals: sharp, flat, natural
- Enharmonics: one sound, several names
- C clefs and reading in every clef
Rhythm
- Pulse, beat and tempo
- Note values and rests
- Bars and simple time signatures
- Dots and ties
- Eighths, sixteenths and counting methods
- Syncopation and off-beats
- Triplets and other tuplets
- Compound meters: 6/8, 9/8, 12/8
- Odd meters: 5/4, 7/8 and beyond
- Swing feel and uneven eighths
Intervals
- Whole steps and half steps
- Naming intervals: 2nd, 3rd, 5th…
- Interval quality: major, minor, perfect…
- Recognising intervals with songs
- Inverting intervals
- Compound intervals (beyond the octave)
- Consonance and dissonance
Scales and keys
- Building the major scale
- Scale degrees and their names
- Key signatures: reading them at a glance
- The circle of fifths
- The three minor scales
- Relative and parallel keys
- Pentatonic and blues scales
- Chromatic and whole-tone scales
- The seven modes and their colours
- Rarer scales: harmonic major, Hungarian, octatonic…
Expression: dynamics, articulation, signs
- Fingering and how it is written
- Dynamics
- Articulation: legato, staccato, accents
- Repeats and navigation signs
- Tempo and character terms: a glossary
- Pedals and pedal markings
- Ornaments: trill, mordent, turn, appoggiatura
Chords
- The four triads
- Building triads on the keyboard
- Inversions and figured bass
- Seventh chords
- Chord symbols
- Extensions: 9, 11, 13
- Voicings: close and open position
- Reading lead sheets
Tonal harmony
- Diatonic chords and Roman numerals
- Tonal functions
- Cadences
- The great progressions
- Voice leading
- Harmonising a melody
- Non-chord tones
- Secondary dominants
- Borrowed chords and modal mixture
- Modulation
- Neapolitan, augmented sixths, chromatic mediants
Jazz harmony
- The major ii–V–I and guide tones
- The minor ii–V–i
- Shell voicings
- Rootless voicings (A and B forms)
- Tritone substitution
- The 12-bar jazz blues
- Rhythm changes
- Modes of the melodic minor
- Reharmonisation basics
- Reading and playing a jazz lead sheet