The nature of jazz has its roots in improvisation. The ''Jazz Sonata'' contains written-out pieces which correspond with improvised figures and formulae of jazz, while at the same time combining specific technical practice material with formal structures borrowed from 'art music'. With these features, the pieces are intended not only for practising jazz musicians but, perhaps even more-for pianists and teachers who, to complement their involvement with popular music, are looking for information and connections with jazz and its practice methods. The pieces are valid as individual pieces for teaching purposes or for use in a programme.