Multi-age or mixed-age classrooms are made up of students from two or more grade levels but grouped under a single teacher. The practice is reminiscent of the old-fashioned one-room schoolhouses, where the same teacher taught students of different ages.
In the modern version, children progress through multiple grades with the same classroom and teacher. As older students move on to another age group, younger students replace them.
Supporters believe that by socializing with different age groups, students learn from and help each other. Students also benefit from the relationships they have with the same group of children over multiple years. Teachers benefit from getting to know their students for more than one year. Students in Montessori schools, for example, are grouped in three to six year spans, such as 3- to 6-year-olds, and 6- to 12-year-olds.