Multi-age classrooms or composite classes are classrooms with students from more than one grade level. They are created when either there are too many students for one class - but not enough to form two classes of the same grade level, or as an educational choice by the school. Composite classes are more common in smaller schools; an extreme form is the one-room school.
Studies of the performance of students in composite classes shows their academic performance is not substantially different from those in single-grade classrooms; instead, outcomes tend to be a function of the teacher's performance.