Why do we teach physics? I’m in a workshop today (run by Dewey Dykstra) about how people change their ideas about the world (I’m going to try not to use phrases like “cognitive framework.”) What do we want our students to know and see?

For many years, there has been a sort of informal folk theory of physics teaching: – “Physics teaching is the presentation of the established canon of physics by approved methods for the benefit of the deserving”.

In other words, why is it that so few students “get” physics? It must be that it’s something that some people can do and some can’t. You have to be smart, and work hard. After all, I’m a physics teacher, and I’m smart, and I sure as heck worked hard, so it must be true. So, as a physics teacher my job is to try to teach to those who have a shot at getting it.

Then back in the 1930’s Piaget came along with his theories of the stages of how children go through certain stages of understanding the world. They’ve got names like sensory motor, concrete operational, formal operational, etc. Basically, they mean … “Formal operational” is when you can do things like manipulate symbols in equations and solve them. So, this gave many physics teachers some sort of research-based “ammunition” for supporting their folk theory – it gave them a way to articulate what “deserving” might mean. If a student wasn’t in the “formal operational” stage yet – there’s no way that thy could “get” this stuff. And if they were, they just had to work hard.

But that’s not what Piaget intended, of course. His “stages” didn’t describe categories to put students into, they didn’t describe the students, but rather ways of understanding. A student might use the tools of one stage in one situation, but another in a different situation. So, the stages were just ways for a teacher to guess what was on someone’s mind by watching what they did. For him, “knowledge is never a copy of reality, but is instead a fallible construction.” In other words, we create an understanding of the world that’s not just some sort of carbon copy of the “real” model, but rather inferences made about the natural laws that govern what it is that we can see. So, they’re a way to derive some understanding of where children are at, not to classify them in terms of some place that they are in terms of understanding, and thus reachable or unreachable.