One plus One consists of 14 solo pieces (Part I) with optional accompaniments (Part II). Each piece is based on a different scale or mode. The solo pieces can be played independently or with the accompaniment, which can be played on the same keyboard. Part I (solo) appears on either the right- or left-hand page, depending on how the players are to be seated at one keyboard. The accompaniments can be played by the teacher or by another student. Some players may also enjoy working with a cassette recorder: the teacher or student can record Part II so that the other player can play Part I with the recording. These pieces are suitable for students of different ages and at different levels of advancement. Notes provide suggestions for practice, background material on the scales and modes on which the pieces are based and ideas for creative activities. A table of scales and modes appears at the end of the book.