Why are the 4th and 7th scale degrees removed from the major scale to make the Pentatonic scale?

That is to say we don't only use these four chords to harmonize in the original key but often change key in a song by moving through he circle of fourths (or fifths). Removing these tones from the diatonic scale reveals the common tones. for a guitarist it reveals common patterns that can easily be moved around.

1. What notes are removed from the pentatonic scale?
2. Which scale degrees from the major scale does the major pentatonic scale use?
3. How does the pentatonic scale relate to the major scale?
4. What two scale degrees are missing from the major pentatonic scale?

What notes are removed from the pentatonic scale?

The concept of the pentatonic scale is very simple and comprises of five notes taken from the seven note major scale. To form the pentatonic scale you simply remove the 4th and 7th notes leaving five notes per octave⁹ .

Which scale degrees from the major scale does the major pentatonic scale use?

A major pentatonic scale is a major scale minus the 4th and 7th scale degrees. A minor pentatonic scale is a natural minor scale minus the 2nd and 6th degrees.

How does the pentatonic scale relate to the major scale?

The concept is very simple: the major pentatonic scale is a collection of notes from the major scale. We know that the major scale has 7 notes. The pentatonic scale chose 5 of these notes and created another scale. When the major scale stops having 7 notes and starts to have 5, it gets the name of Penta.

What two scale degrees are missing from the major pentatonic scale?

The Major Pentatonic is essentially a Major Triad with the 2nd and 6th degrees of the Major scale added, giving us notes 1, 2, 3, 5, 6 from the Major scale. You could also think of it as a major scale with the 4th and 7th degrees missing.