This exercise is the key to playing the "break" (A to B or a to Bb) smoothly and effectively. The left index finger must remain curved at all times and mold to the G# and A keys, as well as the F# ring. This four-minute film shows the steps to take to master Secret 18 (from my book "Clarinet Secrets" Scarecrow Press, 2004): the Left Index Finger Exercise.