This is the third in my series of posts on educational fallacies. You can read all of them here.

Almost all educational settings in the US (and much of the rest of the world) group students by age and then teach those age-grouped students as if they were at the same stage in their intellectual and social development. Most of the time these age groups, in K–12 at least, are divided such that students are within one year of each other in age. Even private school and homeschool curricula assume that "first grade" is a thing and teach to that thing. But does a group of students being the same age mean they are at the same stage in their intellectual development? And do we educate better when students are surrounded by others in the same stage of development anyway?

As soon as we question these assumptions they fall apart. When we question them, we realize that they have no basis in evidence or in logic. And when we explore alternatives, we quickly find that we are likely hindering our students' education when we attempt to group them by similar developmental stage, and when we use age as a proxy for that development.

There are numerous factors that contribute to "developmental appropriateness" for a particular intellectual or physical task, making age a poor proxy for a student's developmental level: a student's biology and physiology, family context, socio-economic background, medical situation, (multi)linguistic context, past educational experience, classroom environment, adult and peer support, etc. None of these, not even the physiological, will be consistent across an age span, and it is impossible that all of them would be consistent for a class full of students. Even the ideal route through the material differs for individual students. Thus, taking dozens (hundreds, thousands, millions) of students through the same educational experiences, in the same order, at the same time, according to the number of years (+/– .5) since exiting the womb, is kind of ridiculous. (Of course, decisions to educate in this way were never based in pedagogical effectiveness, but only in the expediency of industrialized educational institutions "delivering" education to the masses.)

Unfortunately, this age-based model not only rules American public education, but private schools, homeschool networks and curricula, and even religious education have adopted this student-as-fast-food-hamburger approach, following the public school model.

But this use of age as a proxy for intellectual and social development is only an issue because we assume that people should be educated alongside others at the same stage of development. This idea is equally baseless, both in evidence and logic.

As proponents of peer instruction (PI) have found, students often learn concepts better when the explanation comes from someone who recently learned the concept than from someone who learned it years, or decades, ago (their teacher or textbook author). Similarly, students solidify and deepen their understanding of a concept when they are put in a position to explain it to someone else who doesn't yet understand.

These phenomena are not only the basis of recent developments in PI, but they form part of the pedagogical core of Maria Montessori's method, which has been employed in thousands of schools for the last 100 years. In a Montessori classroom (like the one my oldest son attends), students are grouped in three-year segments. Students are given more flexibility regarding when they engage certain concepts. In fact, that flexibility can extend beyond the three-year groupings, as a "second grader" in a class for 6–9-year-olds is free to engage "fifth-grade math" if she is interested, motivated, and ready for those concepts. Further, the wider age groupings means that more advanced or experienced students in the class—who are usually, but not always, the older students—can solidify their learning as they help the younger ones, and the younger ones can learn by receiving not only instruction from their teacher, but the modeling and instruction of their more experienced peers, as well. (Though these techniques were originally based on Montessori's own experience, many have since been verified by empirical studies in education research.)

Much can be said about the power relations that both motivate and grow out of the industrialized, divide-and-conquer, students-as-fast-food, teachers-as-line-cooks model of education. And perhaps I'll follow up in the future on some of those. But for now, I simply want to point out the fallaciousness of these core ideas of our educational system: that age can stand as a proxy for intellectual and social development, and that students should be taught in groups according to their developmental progress. These ideas are pedagogically baseless expediencies for an industrial model of education, and time is past due for us to rethink and replace them.