In a previous post, I discussed some of the principle benefites and possible limitations that might be associated with using ET as an instructional tool within the context of a mathematical college physics course (specifically an algebra-based course). I also detailed my experiences in leading my students through the first four steps of Moses' algebra project (Field Trip, Pictorial Representation, People Talk, Feature Talk). In this post I will discuss my experiences over the next two classes during which I formally introduced my students to Energy Theatre.
The Five Questions:
As I mentioned, I opened up Friday's class by readdressing the 5 questions developed during "feature talk." After reviewing these questions while writing my previous blog post, I realized that many of them (e.g. "what forms of energy are there?", "is energy being transferred?", and "where is the energy located?") were not a far cry from the questions that we might expect an expert or "good student" to ask during a formal energy-based problem solving session. Thus I decided to use these questions as the basis in which to anchor a mathematical analysis the way to bridge ET to the mathematical representation.
As part of their homework, my students had to come up with a complete description of a mousetrap cart using their 5 questions as a guide. By framing the previous night's homework as a test for their questions, I was able to lead a fairly meaningful discussion on what might need to be altered. Section C, for example, decided that "what does energy do?" wasn't terribly helpfull. Meanwhile, section B decided that "is energy being transferred?" should be spun off into "is enery being transformed?" By keeping track of the alterations that each section made, I hoped to instill a sense of ownership in my students.
I opened thenext full day of ET by again readdressing my students' 5 questions. Now that my students had had some experience in ET, I asked them to begin brainstorming, for each question, what types of answers they might expect. All three of my sections had previously generated a question along the lines of "what types of energy are there?" and I had them use this as a starting point. The result of this brainstorm was a list of different types of energy (e.g. kinetic, potential, spring, thermal, chemical, etc.). My sections also all had questions along the lines of "how would we measure the energy?" this question was used to generate a list of possible evidence for the different types of energy (e.g. is there movement? temperature? stretching or compressing springs? etc.).
With these lists in hand, I pointed out that they could also be used to address some of the students' other questions (e.g. "how much energy is there?", "is energy being transformed?", etc.). Again, by having my students continually refine their questions, I was bringing them to a point where they would be able to conduct a mathematical analysis with real teeth.
The Theatah, The Theatah
After our initial reassesment of the 5 questions, I introduced ET and we spent the rest of the day performing ET for the mousetrap cart. The students in my classes had been working in groups of 3-4 up until this point, but I merged the groups in each section into two super groups of roughly 12 students each (my smaller section had 9 each). Some groups were able to finish by the end of class while others needed a few minutes at the beginning of the next to finish.
On the second day of using ET, I gave my students three new situations: My pushing a 2 kg weight across a rough, horizontal surface at constant speed; An activated heat pack; and an activated cold pack. This final situation turned into a homework assignment for the students to practice using Energy Tracking Diagrams. Having spent the first day working out what exactly this ET thing was, my students took to these new situations rather easily.
The bigest difficulty that I encountered was getting my students to figure out exactly what I was asking of them. One group, for example, tried to create a sequence of "pictures" where the ropes represented an initial state and a final state. They kept the number of students constant, but each student was only featured in on "instant." I also had to push many of the groups to come up with ways of distinguishing different types of students (kinetic, thermal, etc.). While many groups figured out different types of movement (my favorites were miming a chemist pouring chemicals for chemical energy, and jumping up and down for kinetic energy), some simply called out "I'm kinetic energy." One group tried to use different regeons within their rope loop to indicate that they were different typed of energy.
A further difficulty which I am beginning to notice now that we are fully involved with mathematical representations is the fact that ET (and ETD's) track the full "trajectory" of energy, while standard mathematical approaches only look at the initial and final states. I'll readress this point as I discuss bringing ET into math. I'm not sure how this will present itself on a mathematical analysis level, but many of my students have expressed some confusion about relating energy tracking to the mathematical statements, dispite being largely able to handle the math.
One logistical difficulty that I encountered was that there were too few of me. Since I had devided my class sections into two groups each, one had to perform out in the hall while the other used the class space (there were too many desks for both to be in the class). While I was able to wander back and forth and ask probing questions about the energy flow and about the ET representation, I got the distinct sence that the group whom I was not immediately attending to were busy in off-topic discussions. This seemed not to be a large issue during the I-RISE since there were three instructors, as well as many observers who functioned as authority figures. The in-service teachers also had a more developed sense of focus and responsibility.
Once my students got the hang of ET, they were able to easily act out the additional situations of the heat pack and pushing the weights. Many of them also told me that they enjoyed the activity and one asked from where I got the idea!
Energy Tracking Diagrams
On the second full day of ET, after my students had acted out the first two ET situations, I introduced them to Energy Tracking Diagrams. Since this was yet a further abstraction of energy flow (an abstraction of an abstraction, really) I demonstrated ETDs for the first ET situation which my students had just enacted: my pushing the weights. I then had my students create ETDs for the heat pack. For homework, I had them create ETDs for the cold pack.
Two immediate benefites I found with ETDs was the ability to "homework-ize" energy theatre and the ability to have students work in smaller groups while still doing an ET-like activity.
Beyond these benefites, however, I found that my students actually had more difficulty with ETDs than they did with ET. Specifically, they were confused about how to represent the object, how to break a complex process into a few descrete stages, how to synchronize energy transformations with energy transfers in their diagrams, and which pieces of energy turn into other pieces of energy ("does K turn to T or is it the C that turns to T during this step?"). Many of these issues did not present themselves during ET. Another difficulty which I observed was that, while conservation is a built in consrtaint in ET, my students were very casual with the number of energy letters in their energy tracking diagrams.
In the end, while ETDs bring many benefites, I felt that spending time coaching their proper use would detract too much from the time I wanted to spend building up a mathematical formalizm. While ET provided a great kinesthetic introduction to energy and energy flow, ETDs seemed to add too much complexity. Perhaps there is a way to succesfully and meaningfully integrate these into a math-based-physics curriculum, however at the moment am not able to.
Bridging ET to Math
I closed out the second day of using ET by formally introducing the law of conservation of energy (Del_E = W + Q + Other energy inputs). I built up to this by generating a law for the conservation of students (Del_N = #Students who cross over a piece of rope). With this equation in hand, it was only a small jump to energy conservation.
The next difficulty was to introduce definitions of Work and Heat and to introduce the mathematical formulations of the varyous energy forms. This was one of the major points of departure from ET; while the theatre could only represent kinetic energy, say, as a group of students making running motions, in a mathematical representation we have to use a particular formula.
Over the next few days, I continued to draw upon the list of questions which the students developed and refined over the course of the week as a basis for mathematical analyses. When I and other expert problem-solvers approach problems from an energy standpoint, we generally have a list of questions we try to address: "what is the system?", "what elements of the system are associated with energy?", "are any of these changeing?", "Is energy being transferred to or from the surroundings?", "if so, how?", "Are there convenient initial and final states to choose?", etc. Each of these questions addresses an aspect of setting up a mathematical solution and many of them were questions which the students needed to address when performing ET. Thus, while the conservation of students inherrant in ET makes an excellent conceptual bridge to a mathematical representation, the act of addressing these questions makes an excellent bridge of practice to using math.
Finally, I mentioned before that one other point of departure from the ET and ETD representations of enery and the mathematical representation is that ET and ETDs attempt to track the full "trajectories" of energy while the cannonical mathematical approach only looks at initial and final states. Again, my students haven't displayed any problem-solving difficulties apart from the standard abilities of this particular population, however some have expressed confsion about this point on a recent "quiz" question "list one thing that you're still confused about."
Some final thoughts:
Overall, I thought my students liked doing energy theatre. Two things that I feel that they have very clearly gotten out of it is a more tangible sense of conservation, and the idea that energy can change forms. Once I begin to discuss energy dissipation and efficiency, I hope to use the fact that students in ET tended to spread out and become thermal. This was an effect that some of my students explicitly pointed out to me and, I suspect, others noticed as well.


















