The ONLY pentatonic scale lesson you'll EVER need

This fourth Fret Science video was originally published on January 16, 2023. As of December 2025, it has received 334k views, making it my fourth-most-watched video. The "rectangle and stack" breakdown of the pentatonic scale ended up being far more powerful than I realized when I made this video, and it has continued to be the foundation that Fret Science is built on.

Original video description: Use two simple geometric shapes to instantly find the major and minor pentatonic scales anywhere on the fretboard. In this video, you'll also learn how to make pentatonic scales sound like music rather than scales, how to instantly turn them into blues and hexatonic scales, and how to fluently move within these scales up, down, and across the fretboard. This video is jam-packed with useful insights. It really is the ONLY pentatonic scale lesson you will EVER need.

The ONLY pentatonic scale lesson you will EVER need Learn the rectangle and the stack and never look back

The major and minor pentatonic scales share the same geometric shape—a two-note-per-string pattern that repeats every five strings. Inside that 5-string pattern are two sub-patterns named for their shapes: the rectangle and the stack. In all of the diagrams, the rectangle is shown in red, and the stack is shown in blue.

When we place the repeating pattern across the fretboard, we must take into account the warp between the G and B strings. In effect, the part of the pattern that lies on the B string’s side of that imaginary barrier is shifted one fret toward the bridge. In all patterns, the rectangle and stack alternate vertically.

Each of the five pentatonic forms contains both the rectangle and the stack, although sometimes they appear distorted because of the G-B warp.

There’s no need to explicitly memorize these shapes, but it can help to know where to find the rectangle and the stack inside them.

To play the rectangle and stack shapes effectively (i.e., musically), it’s very useful to know where the various intervals appear in each shape. The most important note is the root, shown in red, and the shape you’re using will depend on which of your fingers is on the root, and whether the context is major or minor.

In a blues or blues-rock context, if you are playing the minor pentatonic over a major chord, it’s especially helpful to know where the flat third is, so that you can give it a little bend toward the natural third. The roots and fifths are almost always good targets for your phrases.

It’s also essential to know where you can bend. Both bridge-side notes in the rectangle can always be bent a full-step, as can the upper bridge-side corner of the stack. The two lower bridge-side notes in the stack can be bent a step-and-a-half, often to great dramatic effect.

It is worth studying these diagrams to remember which notes bend to which intervals, so that you can effectively target tones with varying degrees of consonance in your phrases. The root and the fifth will always sound consonant and provide good ends to phrases. The natural second is also a great target for adding a little variety. Experiment and use your ears to figure out what you like. A big part of learning to improvise effectively is gaining an aural understanding of how each interval sounds in different contexts.

And don’t forget to add some grease. Bends, hammer-ons, pull-offs, slides, and varying pick attacks are the not-so-secret ingredient for making music out of scale patterns.

To move around the fretboard using the rectangle and stack, we can take advantage of their horizontal connections. The most commonly-used pathway takes advantage of the diagonal connection of the stack to itself, one octave higher.

Here, that pattern is shown overlaid on the Form 1 pentatonic box at the fifth fret. This is equivalently the A minor and C major pentatonic scale. Many famous rock and blues guitar solos are played entirely within this pattern. Eric Clapton and many others have made careers of it.

The rectangle and stack alternate horizontally, with a slight downward diagonal, and this is a great way to move up and down the fretboard quickly. When you arrive at your destination, it’s easy to visualize the vertical alternation of rectangles and stacks to complete the pentatonic form.

The most powerful way to navigate horizontally is to know your intervals inside the rectangle and stack, as well as how the shapes connect. Note that the two figures below feature the exact same sequence of rectangles and stacks. Only the interval names are different.

And, don’t forget that you can quickly switch from the pentatonic scale to six of the seven major scale modes by filling in the missing notes inside the rectangle. This is covered in depth in the Smokin’ Fast Modes video (and expanded in the Hidden In Plain Sight video). In brief, if you’re playing “shape 1”, the minor pentatonic becomes the Dorian mode, and the major pentatonic becomes Lydian. If you’re playing “shape 2”, minor becomes Aeolian (natural minor) and major becomes Ionian (major scale). Finally, if you’re playing “shape 3”, minor becomes Phrygian and major becomes Mixolydian.

Lastly, if you’ve mastered using the rectangle and the stack, it’s easy to extend the pentatonic scale to the blues scale and minor hexatonic scale.

The minor and major blues scale have the same shapes, but the added note (the “blue” note) functions as a flat fifth in the minor blues scale, and as a flat third in the major blues scale. They are best used as passing tones in your phrases.

The minor hexatonic scale adds the natural second to the minor pentatonic scale. The hexatonic scale sounds pleasingly ambiguous to our ears, since we never play the 6th interval, which would pin it down as the Dorian or Aeolian mode.