Tales From a Secondary Implementation of ET

Energy Theatre, as we all have witnessed, is an incredibly salient conceptual model of energy and energy flow within a system. Not only is it used to help in-service teachers develop a deeper understanding of energy, but as a Physicist, it is fun for me to think about how ET might be used to represent ever more esoteric situations (I've had many conversations with Abby, for example,  concerning entropy and energy degredation, and I think I may have a satasfactory way, albeit an impractical one, to represent the negative potential energy. More on that later...) But this all raises the question of how might we use this tool in another instructional context, specifically college physics students.

As I am currently teaching three sections of college (algebra-based) mechanics to students, I thought I would try using Energy Theatre to introduce my students to the concept of energy. And I thought I'd blog about it.

My goals for these posts is to spark discussion about A) is ET something that could reasonably be used at the college (or HS) level and B) what modifications would need to be made, either to ET itself or to the instructional contexts in which it is introduced, so that more naturally fits in a college-level physics class. Secondary goals of mine are to provide some guidence for anyone who may be themselves using or prepairing to use ET in a college setting.

This first post will focus on some of the specific benefites that ET would bring to a college course as well as some of the difficulties that I expect to encounter. I will also provide a brief overview of my first day, which led up to, but did not involve, Energy Theatre. My next post will likely come after my class has mostly moved into mathematical representations of energy.

I should note that none of my students have signed consent forms, nor do I consider them to be participating in a formal study -- Thus I will not provide any information beyond anecdotes of my own experience.

Benefites of ET:
Let me first list benefites of ET. These will be familiar to most. I list them because they support the more formal model of energy encountered at the college level.

• Conservation of energy is built into the representation.
• Energy is represented as having different forms.
• Energy is represented as having different locations within a system.
• Energy can change both form and location.
• Deredation is built into the representation in-so-far as energy tends to become thermal energy and the thermal energy tends to spread both within a system and into the surroundings. 
• Quantization is built into the representation.

Restrictions of ET:
Let me now list some of the restrictions that ET will impose within a college-level instructional context. For each of these, I will briefly describe a possible soluton:

• Energy Theatre lacks a mathematical component.

This is perhaps the most salient draw back of using ET in a college physics class, but hope is not all lost; many aspects of the mathematical representation arrise naturally from ET. The statement of energy conservation, dE = W + dQ, for example, follows directly from the simple conservation of students. Additionally, the identification of different forms of energy and energy transfer that are featured in the mathematics is also present in ET. What doesn't follow from an ET representation are the specific mathematical formulations of the various types of energy (e.g. mgh, 1/2mv^2, etc.) and energy transfer (e.g. FdX, PdV, TdS, etc.). I will have to explicitly introduce these.

• Although in principle, ET can represent the relative amounts of different types of energy, in practice (i.e. using only 10 students) ET lacks a suitable way to describe this. 

When looking at certain cannonical situations ( e.g. orbits, electron excitations, chemical proceses) it is important to look at relative amounts of energy (comparing kinetic to the total, for example, or comparing the total to kT). I suspect that with the introduction of mathematical relations, this will not be a significant problem.

• Potential energy difficult to represent in ET both because it is a negative quantity and because it is not located in an object.

For the second issue, Rachel has suggested allowing the students to use fields as part of a system where energy can go or allowing the students to simply use the system as a whole. I expect that I will have to make use of one of these two modifications as I will want to maintain a certain mathematical rigour. For the first issue (negative PE), I have an intriguing if highly impractical solution: If I allow students to become rest energy in addition to chemical, kinetic, etc. then potential energy can be represented, not as an additional type of energy, but as a deficit in rest energy (for example, students who were rest energy could become kinetic energy). Obviously, I would run into the issue of relative amounts of energy to pull this off. Beyond this, I haven't figured out a satisfactory way of introducing negative energy. Since most situations near Earth's surface can be analyzed using a positive potential energy, perhaps I can get away with only treating those situations.

• What is there to grade (beyond participation)?

Rachel suggested that I also introduce energy tracking diagrams as a gradeable proxy. Good idea!

• Finally, while instructors of the in-service teacher workshops can afford to present energy as a sufficient picture of the world, my implementation will come in the context of a physics course which includes forces, particles, momentum and kinematics. Thus I must treat energy as a necesary, but incomplete picture of the world.  

A Walkthrough of Day 1:
First I should note that the population of students I am teaching are, by and large, sophomore and junior life science majors, though there is certainly a spectrum. Thus many of these students enter my class with an existing familiarity with chemical and biological concepts, such as photosynthesis, electrolysis, chloroplasts, ATP, and photons. Additionally, these students have likely had physics as recently as highschool, and thus already have a passign familiarity with names like "kinetic" and "potential" as well as their mathematical formulation. Also, they are college students who "have" to take a class as opposed to in-service teachers who volunteer to develop their understanding. In other words, there are motivational and attitudinal differences.

For the first day, I took my students through the first four steps of R. Moses' algebra project. First, I led my students on a brief nature walk outside of the physics building. They were instructed to find examples of "energy doing what ever it is that energy does."Because many students are life-science majors, many people identified photosynthesis, wind energy, and solar energy. Many students also identified motion or kinetic energy. The nature walk fo my 2nd section happened to coincide with recess for the neighboring elementary school, so my students got to use kids running around and playing on swings as examples of energy (Says one student: "those students running around have lots of energy" before promptly sitting down on the grass).

This process took about 10 minutes before discussions strayed off topic. The next step was for the students to come up with diagrams of what they saw. Interestingly, there were very little "strobe" immages. This contrasts with what Rachel et al. have seen at this stage of the workshops. Rather, my students drew single pictures of objects (the sun, a tree, a leaf) and had arrows or other symbols indicating an energy transfer of some sort. I was actually quite impressed with these picutres since they included many different processes and often explicitly labeled different types of energy.

For the "people talk" step, I had to push a lot of the discussion about common elements accross the students' pictures. I suspect that this was due to a combination of the nebulousness of this task and my studnets being college students.

For the fourth step (and the final one of the day), "Feature Talk,"  I had my students brainstorm "a list of questions that if answered, would provide the most informaiton about what energy is doing in each (or any conceivable) scenario." (this was the same prompt given in the EP workshop). My students generated many great questions and each section narrowed down a top 5 (presented by section):

1. How is energy measured? How is energy transformed? How much energy is there? Where did it come from/ where did it go? What forms of energy are there?
2. Where did the energy come from/ go? How can we measure it/ how much energy is there? What types of energy are there? Is the energy being transfered? What is the form/ state of the object? 
3. How is the energy measured? What forms of energy are there? How is the energy transfered? Where does the energy come from? What does the energy do?

Many of these questions are excellent! Though some of them are quite big or too philosophical. (I had to dissuade my 3rd section from using "what is energy?" on the grounds that it wouldn't add anything to an analysis of a system). I told the students that these would remain provisional lists and that they should feel free to modify them if other questions occured during our exploration of energy.

I left my students with the following homework assignment:
Watch the following video of a mousetrap cart and generate as complete a description of the energy within the cart as possible. Use your section's list of questions as a starting point, but also consider this a test for the list -- are there other questions that you find that you need to ask? Are there questions that you find that you don't need to ask?
Be as thorough as you can; be prepaired to use your description in the next class.

... this, of course, will form the basis for the students' first encounter with Energy Theatre.