Watch the Pentatonic Scale online guitar lesson by Brad Carlton from Melodic Patterns
Pentatonic Scale Example 18 demonstrates the principal of playing triplets with two different pitches. It's low-high-low and then it's high-low-high where you are changing strings. So make sure you see the pattern in terms of both the low and the high side of the scale, but let your ear come into play immediately. Practice these with alternate picking and remember the picking will turn around – the first triplet will be down-up-down, the next triplet will be up-down-up. After you've mastered that, reverse your picking scheme.