SPOILER ALERT: Do not read the following post if you have not yet read the Swackhamer article posted here. You should come to your own conclusions before reading mine.
Fair warning given, I finally read this on the plane home from Maine, and have a few thoughts...
When Swackhamer argues against form, I think what he is really arguing against is the misconception that a particular form is always associated with a particular kind of object, in other words, a straw man. This is particularly evident in his information analogy: “…it would be nonsense to say that hard disk information is transformed into wire information and then into RAM information and then into CD information.” Indeed, it would be nonsense to say this, but the analogous thing to say about energy would be that it is transformed from hand energy to box energy to floor energy, and this is such nonsense that even our most confused students don’t say this. I almost get the sense that Swackhamer himself has the misconception that particular forms of energy are always associated with particular objects. He sees that it leads to nonsense, but instead of recognizing his misconception, he tries to eliminate the notion of form.
I think he makes a very important point that what we really need to pay attention to in energy transfers is how gaining or losing energy changes the state of the object. But the way I understand the idea of form is that it is a shorthand for describing the state of the object in exactly the way he talks about. If an object has kinetic energy, it means it is moving; if it has thermal energy, it means its molecules are moving; if it has spring potential energy, it means it is compressed; if it has gravitational potential energy, it means it is separated from the Earth; etc. Having this kind of shorthand for the state of an object is important because it makes it easier to systemically represent it. One thing I don’t like about his representation is that the state of the object, which he says is a very important thing that you should always ask students to think about, is not actually part of the representation, so it requires a huge amount of cognitive work to hold it in your head. At least it does for me, and I assume it would be even worse for students. The representation doesn’t actually represent one of the most important things.
Furthermore, his representation doesn’t even represent conservation of energy! As he mentions several times, you have to remember that energy is conserved, and then infer from the diagram that if the arrows in a chain are not the same size, then one of the objects is gaining or losing energy. Not exactly what I’d call intuitive or helpful.
He essentially admits these two failures of his representation in the following statement: “Energy flow diagrams are good for making inferences, so long as students are committed to a hardy energy conservation concept and the fact that energy must always be a state of some system.” What good are they for learning if they can only be used if students are already committed to the two most important and difficult concepts about energy? Energy Theater (along with Emma’s movies and the diagrams the students draw after doing ET) is a superior representation because it forces a commitment to both of these concepts, rather than being conditional on that commitment.
well argued.
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