Watch the Week 1: Modal Classification online guitar lesson by David Wallimann from Playing Modal Made Easy

By looking at the major modes, we find 5 notes in common.

These 5 notes give us the following major pentatonic scale:

R - 2 - 3 - 5 - 6

The same thing can almost be done with the minor modes (the Locrian mode won't work).

These 5 notes give us the following major pentatonic scale:

R - m3 - 4 - 5 - m7