1-2 · Music Theory: Octaves, Chords, and Scales

Learn the small set of music-theory terms you'll lean on for the rest of the course — pitch, octave, pitch chroma, the chromatic scale, chords and arpeggios, scales, the pentatonic scale, and the root — all explained from scratch with no prior theory assumed. By the end you'll know exactly what a phrase like "the E minor pentatonic scale" actually means.

Some definitions that will be useful throughout the course:

• Pitch - How high or low a musical note sounds.
• Octave - Notes separated by 12 frets (equivalently, 12 semitones). When two notes are separated by an octave, one sounds higher than the other, but they also share a certain core quality (their pitch chroma).
• Pitch chroma - In Western music, there are 12 pitch classes, each with a unique tonal color, or pitch chroma. We know these 12 notes as the chromatic scale: A, A# or B♭, B, C, C# or D♭, D, D# or E♭, E, F, F# or G♭, G, and G# or A♭.
• Chord - A collection of two or more pitches, usually played at the same time. Most chords contain 3 or 4 notes.
• Arpeggio - A chord played one note at a time in sequence (the order doesn’t usually matter).
• Scale - Any collection of notes within an octave range. A pentatonic scale contains 5 notes. The major scale (and many others) has 7 notes. As mentioned above, the chromatic scale has 12.
• Root - The most fundamental note of any chord or scale and the one that gives the chord or scale its name.