Exercise no.16 is to be skipped, for this moment at least. My master decided to set it aside too, probably due to the difference of difficulty between the previous and the next exercises. So let’s respect the tradition and wait for at least two or three lessons before resuming it.
Here we are at exercise no.17: still based on the five notes, it is worded in order to make that left hand move, because too often it is wasted. During this exercise you will have to play by this hand nearly solely one movement notes . The right one will play 4 movements notes instead. In the last two measures of the 2nd line the roles reverse, then they return to a solution similar to the beginning.
Exercise no.18 is a three four time one with right hand playing the melody, while the left one plays some two notes chords. In fact, the trickiness will stand in playing two notes at the same time.
Follow the video for more clarifications.