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Day 4 of Physics Teacher Camp: Avengers Assemble!

July 11, 2011

The title of this post is a shout-out to Brian Carpenter, who really helped me to think a bit more deeply the art form that is the comic book and also figure out the comic book alter egos of some of the participants of the conference. I’ll spare you (and us) from most of the comparisons, but I had to share just one:

The resemblance is also more than cosmetic; just as Charles Xaiver uses Cerebro to locate and connect mutants to save the world, Frank uses the internet to bring physics teachers (who some might view as mutants) to save the world. I also think there’s one more resemblance that I should point out:

One last comic book story I’ll share from the education I got from Brian last night. When you look at the comic book superheros, in many ways, they are our modern myths. Look at the DC comic book heros, Superman, Batman, Green Lantern, Flash, Aquaman—many of these characters are almost direct copies of Roman gods (flash=Apollo, Auqman=Neptune, etc) they are also perfect in such a way to be inapproachable. Batman as a ultra rich, ripped, gadget freak who fights crime, or Superman as an all powerful alien, who can relate to these characters? This sort of puts the whole premise of the title Waiting for Superman in a whole new light for me. If we really are waiting for Superman to come and fix the school system, and solve the problems we cannot solve, this seems to be a misguided strategy—a point nicely made in the blog post, Why Superman would Suck as a Teacher.

Contrast this with the Marvel superheros—flawed humans who are constantly wrestling with their flaws to become better people. Hulk who is always battling to control and use his anger, Spiderman suffering from girl problems and social isolation, Thor who hubris and war-like nature gets him cast out of Asgard. These are superheros with human emotions that we share, who must overcome their limitations to save the world. And when they unite in the Avengers, they can save the world. This is certainly how I’d like to see myself—as a flawed teacher, who can overcome these flaws by uniting with other teachers around the world, and ultimately change the world together.

The last bit of physics teacher camp definitely took on a bit of this Avengers atmosphere, with us picking up on the educational reform thread from the the night before, and brainstorming ideas for a letter to Carl Weiman, a nobel laureate and advocate of science education reform to inform him about modeling instruction and ask for his support. The big takeaway was that we need to share more stories of students who are transformed by this method of science teaching, and foster stronger connections between teachers through sharing.

Of course, this is just the beginning. Matt showed us mock-ups of the AMTA site redesign—which promises to allow teachers to connect with one another, share and revise materials, and discuss teaching. This promises to be an incredible resource for teachers everywhere, and if you haven’t joined AMTA yet, you definitely should—it’s the best $25 you could possibly spend to help make this vision a possibility.

More tidbits

  • Here’s a great little explanation of functions that would make a wonderful poster on a wall:
    • If the change is constant it’s linear.
    • If the change in the change is constant, it’s quadratic.
    • If the change is proportional to the thing itself, it’s exponential.
    • If the change in the change is proportional to the thing itself, then it’s sinusoidal.
  • We talked about standardization—should students be told to do all their measurements in SI units, or in cm instead of meters? Should we tell students which thing to plot along the axis? Matt made a powerful argument that we want students to discover the reason for standardization, and there’s no better way to help students to see this than to let them go off and make measurements in whatever unit and graph quantities on whatever axis they choose, and then ask them to compare their results, which will force them to instantly look for an example. In the buggy lab, for instance, when they have graphs of x vs t and tvs x, in all sorts of different units, just ask “which buggy is fastest?” and watch as students scramble to compare their results and develop a standard.
  • We had a very interesting discussion on scaffolding that I’ll probably turn into a longer blog post, but my main takeaway was that if you want students to learn to work without scaffolding, the gradual removal of the scaffold doesn’t work too well—the gradual changes are too subtle and students can’t recognize them. Better to do things like giving students 3 problems in a single day, one broken down into parts, the next with a simple checklist (model this completely by: drawing appropriate diagrams, deciding which model applies, etc) , and finally one with no question at all—a true goalless problem, and have students work on all three on the same day.
  • Matt Greenwolfe showed off this awesome vpython program for visualizing the surface charge on a wire. Here’s a quick demonstration:
  • Once I get permission from Matt, I’ll post the code here as well.

  • Kelly shared an awesome project she does with her regular class build a scale model of a roller coaster using 1 m of wire. Students must create a roller coaster with certain parameters, and show that it the acceleration doesn’t exceed certain values. As is my habit, I’ll give her a shout out in hopes she posts this great project and some photos to her blog.
  • Brian had this great idea for a project—have students study cartoons and write out 5 laws of physics for a particular cartoon world (eg. The gravitational force doesn’t act on you until you look down. Then write a program in vpyhton on scratch to model this world).
  • We also had a further discussion of the LOL diagram and system schema, and one particular subtlety. For the case where you have an system where the separation distance between an object and the earth is changing, it really doesn’t make sense not to include the earth in the system. Here’s why: if the earth is in the system, then the object and the earth interaction stores gravitational potential energy, and this is fine. But if only the object is in the system, you might be tempted to say that the earth is doing work on the system consisting only of the object. This would also imply that the earth is transferring energy to/from the ball, and this doesn’t make sense. If the ball is falling, the energy transfer taking place is from the gravitational potential energy of the earth ball system to the kinetic energy of the ball. This shows that the typical LOL diagram isn’t really equipped to correctly describe what is going on for these types of systems, which I found to be a great example of a sort of model-breaking, and thought it might be cool to help students recognize some inherent limitations in the tools they use to describe the world around them.
  • And finally, an couple of great lines for posters from Mark and Kelly:
    • Fail often to succeed sooner.
    • Frustration is your mind constructing understanding.
7 Comments leave one →
  1. July 11, 2011 6:54 am

    Recently saw Megamind at a free-movie event at local theatre. Loved the film because the good guy burns out, and the bad guy becomes the good guy and hero. None of us is all good or all bad. We have both within us – it’s what we practice that becomes permanent.

    Thanks to you all for convening the Physics Camp on behalf of deep learning and practicing good. You are the heroes.

  2. July 11, 2011 8:25 am

    Earth transferring energy to the ball might not seem to make sense, but I’m not sure this breaks the model. Why does Earth exerting a force over some displacement of the ball not transfer energy? I don’t have a problem with Earth doing work.

    Of course, one could say that the energy is transferred from Earth’s gravitational field to the ball, but this is not where you want to go with sixteen year olds (not most of them, anyway). But as soon as you start talking about fields and energy, you’re really getting darn close to discussing potential energy, so I figure why not throw everything in the system and be done with it?

    I’m just missing why leaving Earth outside the system “breaks” the model.

    • July 11, 2011 5:38 pm

      I don’t think it breaks the model—it breaks the diagram. The energy flow arrows energy transfers between objects, and if you draw an arrow from the earth to the object, you are indicating that you are transferring energy from the earth to the object, but that energy is really stored in the field, not the object. Or at least that’s how I understand what Matt was saying. Maybe he’ll comment on here and clear things up for me.

      • Matt Greenwolfe permalink
        July 25, 2011 5:44 pm

        Seems like I’m constantly getting back to comment on these blogs days or weeks after the discussion has gone cold. Don’t know that I’ll ever keep up! But I hope someone will still check in to see this and bring the discussion back alive.

        Anyway, as I see it, the main point to keep in mind is that we are defining energy as the “ability to cause change.” In any energy transfer, this means the system “losing” the energy must change, and the system “gaining” the energy must also change whenever energy is transferred. This is the key point the modeling materials keep making. Tying energy to changes in real systems is important in order to combat the unreality and mysteriousness attributed to it by the typical school science energy concept.

        So when an object falls closer to the Earth, does the system of just the Earth change? I would argue that it doesn’t. The relative position of Earth and ball have changed, but the Earth itself has not.

        We can play games here. Using other forces, anchor the Earth (or more generally one of two interacting masses) so that only the other object can move. When released, the second object will end up with all the energy, storing it as kinetic energy. One can switch the objects, or allow both to move so that each ends up with a portion of the energy. One can play games with frames of reference, but the overall conclusions are the same.

        Now, what about the field? It definitely does change when the object’s relative positions change and is rightly seen as the real repository of the energy. But so far as I know, and I admit there’s some deep physics about field theory and gravity that I don’t know, this particular energy stored in the field by the relative position of these two objects is only available to these two objects, as described above. It can’t be transferred to a third object, leaving the two objects in place, the field somehow changed, and the third object careening off with greater KE. So even if you do include the field, it doesn’t resolve the problem that the system storing the energy is the two objects and their fields together, not just the field itself. A system including just the field also does not make sense.

        This is all the result of thought questions posed by Greg Swackhamer and it sure seemed this was the direction he was leading, although I can’t vouch for what he thinks about the situation because in true modeling fashion he just posed questions that made me think really hard about it.

        On a more practical level, I have trouble explaining to students why an arrow should be drawn from Earth to ball when the ball falls. The best I can come up with is to give the student a dollar and keep a dollar myself. Now together the student and I (two person system) have two dollars. If the student gives me a dollar, now I have the two dollars. If I want to choose a single-person system, just the student or just me, then the transfer arrow has to be one dollar from the student to me. This is still different than the way we think of it scientifically, where we would attribute a transfer of two dollars to the arrow, calling it the work done by the student.

        To extend the analogy to a depth I’ve never attempted in a conversation with a student, suppose the two dollars is stored in our joint bank account, available only to the two of us and no-one else. Then I take both dollars out of the account and spend it on something. This is not quite a full analogy with the field, which is affected by all the masses in the region, even though this portion of the energy is still only available to these two masses.

        I’m confusing even myself now! The only non-confusing thing in the whole mess that I can see is to put both objects and the field into the system.

  3. rhettallain permalink
    July 11, 2011 10:08 pm

    Although some of the x-men were Avengers, Professor X was not. Just think you should know. Maybe you could change your title to “X-Men Assemble!”

    Really, I just think Beast and Wolverine were in both x-men and avengers. I could be wrong though.

    • July 11, 2011 10:11 pm

      Yeah, I’m enough of a comic book geek to know that myself, still the resemblance to professor X is so uncanny, that I had to go with it. Brian had a few other comparisons to the Avengers, but I can’t quite remember them.

  4. July 12, 2011 1:12 pm

    I had a little trouble with
    If the change is constant it’s linear.
    If the change in the change is constant, it’s quadratic.
    If the change is proportional to the thing itself, it’s exponential.
    If the change in the change is proportional to the thing itself, then it’s sinusoidal.

    The first three look ok to me, but the 4th differential equation has other solutions. For example, exponentials also fit. Of course, sinusoids are a special case of exponentials, once you introduce complex numbers, but I don’t think AP Physics goes that far in math.

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