Keys to include a few in five flats and sharps, more difficult passage and scale work, more antiphonal detail, sustained inner or lower voices, pedal notes and wider skips in L.H., melodies and counter-melodies, melody and accompaniment shared by hands or working independently, test of interpretative skill and pedalling devices. Graded tests show how to reduce horizontal harmonies, to connect melodic lines, spot key changes, pedal for different effects.