During the 90's many schools began experimenting with multi-age classrooms, with the intent of targeting instruction at children's skill levels rather than ages. Education Week reports this week that grade-by-grade testing mandated at the federal level precludes--or at least severely constrains--the possibility of regrouping children in new ways. According to the Kentucky Department of Education, which keeps statistics on this matter, the percentage of elementary schools that use exclusively single-grade groupings has doubled from 24% to 48% over the past five years.

While proponents of multi-grade grouping says that it helps students learn faster and improves their socialization by allowing them to model leadership, critics worry that teachers teach "to the middle" while older students end up becoming "tutors" rather than learning themselves. We haven't seen any evidence on multi-age grouping and student achievement, but it's interesting to note how trends come and go.