The blues scale — one more note

Take the minor pentatonic and add a single note between two of its steps, and the blues sound appears. One note changes the character of the entire scale.

That note is called the blue note. It deliberately sits outside the major/minor grid, in the half-step gap, which is why it sounds tense — played in passing, not as a destination. That friction is the blues sound. Pentatonic plus blue note gives the blues scale.

This section stays short because nothing new begins here: it's the pentatonic scale from the previous section with one added note.