Jazz Music
Lesson 1 - chord extensions and flattened fifth chord.
Chord extensions are where extra 3rds are stacked on top of a triad to produce 7ths, 9ths, 11ths and 13ths.
Chord extensions are typical in jazz music and make it distinguishable from other types of music.
Notes for improvisation
A, C, D, E, F

Root
Third
Fifth
Seventh (minor)
Ninth
Eleventh
Thirteenth
Major triad chord
Extensions
Listen to Bill Evans's 'Waltz For Debbie'. It's full of chord extensions!

Lesson 2 - key signatures and the circle of fifths
Key signatures tell you which key the music is in.
Circle of fifths in music theory, the circle of fifths (or circle of fourths) is the relationship among the 12 tones of the chromatic scale, their corresponding key signatures, and the associated major and minor keys.
