A Blues Scale

Play A-C-D-E flat-E-G-A. Leave out E flat and you have A minor pentatonic: A-C-D-E-G. The blues scale inserts one note into a five-note framework, giving you six different notes before A repeats.

Some lessons use "blues scale" for other related note sets, including major blues. Here the name refers specifically to the common minor blues scale.

In this six-note version, E flat is the added flat fifth above A. You may also see it written as D sharp: both names point to the same piano key, although E flat describes its position as a lowered fifth.

Play D-E flat-E, then D-E. The E flat adds a brief point of friction between two familiar notes. Letting it move to E makes the gesture easy to hear; holding it against an A chord creates a stronger clash. Neither move is forbidden. The timing tells the listener what you meant.

In performed blues, "blue notes" are broader than one fixed piano key. Singers and players who can bend a pitch may shade the third or other notes between the keyboard's fixed pitches. The six-note scale is a useful playing map, not the whole sound of blues.

Try A-C-D-E flat-E, then G-E-C-A. Play E flat briefly and give E or A a longer duration. On the next pass, omit E flat. You can now hear the difference made by one note without changing the whole phrase.

If an A7 chord is underneath, listen to C natural against its C sharp. That rub is common in blues, but a long C can sound more exposed than a quick one. Pentatonic and Blues Scales explains how chord tones and blue notes meet.