The Blues Scale
The blues scale is defined in terms of the major scale, as shown below.
[Image #1: CbluesScaleCMajorScale]

Play it on your instrument now. Notice that the blues scale has only 6 different notes. This adds a degree of simplicity, and yet fluidity, to its implementation. It is the only western scale that has two consecutive half steps, from 4 to #4 to 5. Proceed to The Blues Scale assignment, and write out your blues scales in all 12 keys.