John Thompson's "Modern Course for the Piano" (5 volumes), published in 1937, is recognized as one of the most widely used piano methods in the world. It is particularly noteworthy for its strong support from instructors of not only classical but also jazz and popular piano. In Japan, a licensed edition from Willis (translated and edited by Masayasu Oshima) was released by Zen-On in 1972 and has undergone numerous reprints to date. Volume 1 ("Modern Course for the Piano, Book 1") in particular has a large circulation, being a long-seller with 208 printings of the Zen-On edition as of 2021. All 50 pieces in this Volume 1 have a second piano part written by Thompson himself, allowing the entire book to be performed as two-piano compositions. How many people are aware of this fact? Despite Thompson repeatedly emphasizing the importance of incorporating duets and two-piano playing into lessons in many of his method books, their introduction and practice in Japan, at least, seem far from sufficient. Only the Zen-On edition of "Teaching Little Fingers to Play Ensemble," the accompaniment book for "Teaching Little Fingers to Play" is barely utilized. The following five collections feature accompaniment parts written by Thompson himself:

• Teaching Little Fingers to Play Ensemble (4-hand duet / 2 pianos, 30 pieces)
   Teaching Little Fingers to Play Ensemble [Willis Music, 1937 / Zen-On Licensed Edition 1972]
• Second Piano Accompaniments for use with Modern Course for the Piano, First Grade Book (This work, 50 pieces)
   Second Piano Accompaniments for use with Modern Course for the Piano, First Grade Book [Willis Music, 1950]
• Second Piano Accompaniments for use with First Grade Etudes (24 pieces)
   Second Piano Accompaniments for use with First Grade Etudes [Willis Music, 1950]
• Two Piano Album for the First Year (12 pieces)
   Two Piano Album for the First Year [Willis Music, 1950]
• Second Piano Accompaniments for use with Studies in Style (25 pieces)
   Second Piano Accompaniments for use with Studies in Style [Willis Music, 1950]

(In addition to the above five items, there is also "A Tuneful Duet Album for the First Year" (11 pieces) [John Thompson Jr. : A Tuneful Duet Album for the First Year, Willis Music, 1940] written by Thompson's eldest son, John Thompson Jr.)

The second piano parts written by Thompson himself demonstrate the free creativity characteristic of the original composer. They are not limited to safe accompaniments that merely reinforce the original harmony or trace the melody in parallel octaves. Instead, each piece is meticulously crafted, incorporating elements such as the extraction and expansion of inner voices and motives from the original piece, contrapuntal interplay, and the introduction of novel figures, making each a substantial two-piano work despite its small scale. This serves as a great encouragement for learners, and their awareness when returning to the original piece alone will fundamentally change. Instructors, too, will often rediscover teaching points in the original piece through the experience of two-piano performance. If one has access to two pianos but conducts one-way lessons without utilizing these second piano parts, it is an immense waste of opportunity. It is highly recommended to utilize them effectively and for students and teachers to enjoy ensemble playing together. Thompson's own preface to the second piano parts is introduced below in my humble translation. It is worth listening to as a confident proposal from a rare educator.