The Elbow Elevator
The elbow acts like an elevator: carrying its passengers (the forearm, wrist, & fingers) Up and Down to bring them to the right level for each string.
The elbow elevator only goes up and down, it’s not an escalator that moves side to side!
Remember to keep the wrist flat, so that it’s always in line with the arm.
Practice this a few times, then move on to the next page.