The "A+ Club" is a motivational technique, which is intended to encourage younger piano students to maintain daily practice excellence. Since only piano students receive a grade at each lesson, the "A+ Club" applies only to piano students. (Adults do not receive grades.)
Those students who earn the grade of A+ can place a sticker on the A+ Club Chart that week. When a student earns four stickers in a single month, he/she has made the "A+ Club" for that month.