As with many students that come from a classical background, it is a difficult transition to learn to play Blues & Jazz.  When a musician improvises, they usually have a variety of riffs or phrases that they have developed and learnt over a period of time and can access these phrases instantaneously whatever key they are playing in to create a seamless improvised solo from the phrases they have learnt.  The composer's idea for this book is create phrases or riffs over two measures of various Blues progressions.  By sub-dividing each ot the 12 Bar Blues progression in the book, he gives a choice of the different phrases or riffs the flutist can use.