The movement towards multi-age education claims to have evidence that the idea boosts intellectual and social skills. But its momentum is being threatened by planned national curriculum requirement s and stringent standardised assessment tests that are all designed to be age-specific.
Nancy Walser, editor of The Harvard University Education Letter, whose own kindergarten-age daughter is in a multi-age programme in a public school, said: "Multi-age education is going to continue to be an option, but it's going to depend on the level of strictness that districts decide to follow and on the power equation: are we going to let teachers do what they need to do to educate the kids or are we going to impose all these standards on them?"
Mixing students from two and occasionall y three year groups in one classroom ostensibly improves learning through co-operation, mentorship and knowledge-sharing. Teachers remain with the same students for two years instead of one, and older students serve as unofficial mentors to their younger classmates.
"As a parent you can see that a younger child is much more interested in what an older child is doing than a teacher or a peer," Ms Walser said.
In many schools, students are increasingly mixed by age on a part-time basis. "A third-grader [eight-year-old] will be teamed with a kindergartener who may not even be reading yet, while the second- or third-grader may still be in the process of learning about vocabulary," Ms Walser said.
A succession of studies have shown that students in such programmes show at least a slight improvement on achievement tests and tests for mental health.
Bruce Miller, a researcher at the Northwest Regional Educational Laboratory in Portland, Oregon, said: "In the affective area - attitude, relationships and interpersonal regard - the statistical evidence tends to favour the multi-age classroom."
But no sooner has the movement started gaining speed than events have begun outpacing it.
Multi-age classrooms are harder to teach and require more preparation and training at a time when there is a growing shortage of educators. And new assessment tests, due to start nationally in 2001, will be strictly tailored to specific grades.
The irony, said Bruce Miller, author of Children at the Center: Implementing the Multi-Age Classroom, is that single-age grades date from the 19th-century population explosion, when Americans moved from the one-room schoolhouse to "industrialised education, which we're all sort of fighting now".