Here are some variations on the basic shuffle pattern. This next one requires the use of the fourth finger at the fifth fret.
This idea comes from a boogie piano left hand pattern. The progression here is a common form of the 8 bar Blues.
Here the new notes from the previous two exercises are combined in a single note riff style. The final two bars of this exercise depart from the riff and introduce a new phrase which ends on an E7 chord. This is called a turnaround.