Our objective with these lessons is to give you the tools, understanding, and confidence to improvise with your left thumb while the right thumb "holds down the fort". Here is another suggestion for the type of thing your left thumb could do. The first three measures are almost the same for the left thumb - measure 1 goes up the scale fragment, measure 2 goes down the scale fragment, and measure 3 goes back up. Measure 4 on the left is different, emphasizing B as the first and last note of the little phrase. Again, B is a good note to play here as the right hand is playing a partial E chord.