Blues Slide Guitar: Pentatonic Scale. Part of the series: How to Play Blues Slide Guitar. The pentatonic scale or blues scale is an essential guide to playing blues slide guitar. Learn to play the notes of the pentatonic scale in this free instructional video on slide guitar playing from a professional musician and songwriter. Read more: http://www.ehow.com/video_4538631_blues-slide-guitar-pentatonic-scale.html