Everyday Ideas–Pee Theory

One of the powerful ideas we’ve had in inquiry class this semester is called “Amy’s Pee Theory”. It’s an idea we’ve returned to again and again in explaining phenomena. Amy’s pee theory states that if you pee a normal size amount in a very large pool, no one will notice. The pee (to be sure) is still there, but it’s been spread out over such a large thing, that it’s not concentrated enough to have a noticeable effect. Peeing in a smaller container of water, such as a toilet, results in a more obvious effect (yellow color), because the pee is concentrated in a small container. This idea is our class’s instantiation of beginning to think about a thermal reservoir.

Last week, our class discussed the energy tracking of a battery-powered fan. We spent most of our time trying to decide whether the room’s thermal energy increases, decreases, or stays the same. We touched upon lots of everyday experience–running the thermostat in your house switched to “A/C”, “Heat”, or just “Fan”; actual temperature vs. “feels” like due to wind chill, fanning to “cool yourself” off, you don’t seem to cool down the room; how the moment you stop fanning, the cool feel goes away; how ridiculous it seems that you could really cool off a room by having lots of people fanning, vents in your car, etc.

Eventually, people were convinced that fanning didn’t actually reduce the temperature, but we didn’t have an explanation for why you felt cooler. The idea that was eventually was proposed was, “Fanning helps the thermal energy you’ve produced around you go away, by blowing the warm air away from you.” Several said that there mind was blown at hearing that idea.

Eventually,everyone agreed a room should technically get hotter, but you wouldn’t be able to tell via “Amy’s pee theory.” The room is so big that the little bit of thermal energy put off by the motor wouldn’t make a big difference. This nicely motivated why we should try the experiment with a fan in a very small “room”. So we ran a fan inside a small cooler for 10 minutes while we went outside to make moon observations, and the temperature inside the cooler had risen by 12 degrees. Pretty cool. Upon opening the cooler, pretty soon the cooler was back to being normal temperature, because the “pee” that we had kept trapped in a toilet had now spread out into the pool. The room was not measurably hotter as a result.

After the experiment, someone blurted out remembering a long time when their house had been flooded.  To dry out the house, they had to bring in dozens of industrial fans, and they recalled how freakin’ hot it made the house. Bringing in dozens of huge fans was like getting several bus full of kids to pee in the pool. 

Sometimes, things go well…

My inquiry class is going quite well this semester. The skills that this class has picked up quickly and use regularly include

– Re-voicing and paraphrasing what others are saying

– Asking questions about others’ ideas to get more information

– Asking questions to make sure we understand each others’ ideas

– Summarizing, comparing, contrasting different ideas that have been said

– Telling someone if/when their ideas make sense (even if one don’t necessarily agree), and why it makes sense.

– Talking to each other for extended periods of time (without looking at me).

– Using tone of voice / eye contact to indicate interest, care, and humility (rather than dismissal, indifference, and righteousness)

– Posing honest questions and making honest statements

– Using tone and body language that communicates that everyone is free to change their mind

Part of this reminds me that “being” a good listener and “being” engaged consist of things you actually do. But I’m also reminded of just how easy it is for everyone to do these things when everyone feels the right way–feeling safe and having a sense of belonging. Of course I know that there’s feedback between feelings and behavior: the students feel the way they do because of they way we are all behaving, but we are also behaving these ways because of the way we feel. It’s mutually reinforcing. And, of course, when these feedback loops are going the right way, it seems easy, like how could it be any other way. But I know that other times, when the feedback loops are going the wrong way, it can seem impossible. Cherish the good times.

Brain Dump: Good Argumentation / Never Used Before Talk Move

One of the topics we teach in second semester physics is blackbody radiation. The typical kind of scenario students would be asked about is, given the temperature of a star and information about the size and orbit of a planet, determine how much energy arrives on the planet each second. One of the main difficulties students have is deciding how to use the relationship that intensity = power/ area. There are lots of different energies, areas, and intensities to consider, so students who are used to plug-n-chug can easily fall apart here. Since we introduced the topic two weeks ago, I’ve been starting each day with various discussion (clicker) questions asking student to think about intensity, energy, and power qualitatively. We’ve had lots of good days of discussion stemming from this and progress is certainly being made, but students’ handle on the ideas seem to be quite elusive and fleeting with lots of side-steps and backslides, even for the students who don’t usually struggle.  On Thursday, I asked the following question to start our day, which pulled us into a really good discussion that lasted 15-20 minutes or so:

Assume you know how much energy is emitted from a star each second, Es. You want to find the intensity of the light arriving at a planet. Which calculation should you use? The question included a diagram that showed three distancse: Rs, the radius of the star, Rp, the radius o the planet, and Rsp, the distance between planet and the sun. The four options where.

A. Es/ 4πRp²

B. Es/ πRp²

C. Es/ 4πRsp²

D. Es/ 4πRs²

Students thought to themselves, voted, and then talk in groups. When students re-voted, we were split between B and C, with a few unsure whether it was A or B. We’ve been getting used to these kinds of discussions, so I asked a few students to explain why those chose B.  The basic line of reasoning was that we were interested in the intensity at the planet, so the relevant area had to be the area of the planet, because the planet that was catching the energy with its cross-sectional area.

Instead of letting people voice an argument for C, I said that those who picked C had to explain what they was wrong with B without explaining why they thought C was correct. I motivated this by talking about why so many hot button issues arguments are unproductive, such as abortion rights, whereas everyone just keeps repeating their arguments without listening to the other side.

One really nice argument, which ended up being convincing to most in the class, was this:

– Es/ πRp² says in words that you are taking all the energy from the sun and spreading it over the area of the planet. This can’t be right because not all the energy from the sun gets to the planet. In fact, most of energy misses the planet because it goes off in other directions.

I made sure at least one other student could repeat the argument, and then another argument was made: This argument was about how we could actually “correct” the equation so it did give the intensity at the planet. The argument was that if the “area” you want to divide by is the area of the planet, than the numerator has to be energy arriving at the planet Ep, not Es. Intensity *is* an energy divided by an area, but to get the intensity of the planet using the area of the planet, you have consider the actual energy arriving at the planet, so it would be Ep/πRp².

By the time we got around to asking for arguments for C, most students were convinced it couldn’t be B, but formulating good arguments for C was hard, and it took a bunch of back and forth among the students before a really compelling argument to emerge. The discussion was really juicy and students were really listening, but I had a feeling that while the “class” a whole was getting it, many students still needed an opportunity to pull it together, consolidate. So I had students vote with thumbs up, thumbs side, and thumbs down, whether their understanding was , “I understand the reason why it must be C, and could explain it,” “I think I understand why it must be C, but I’m less confident I could explain it someone else,”, “I’m still not sure I understand why it must be C”. The room was split about half between thumbs up and thumbs to the side. I said if your thumb was to the side you had two options: you could look to a person with their thumbs up and tell them that you want to practice explaining it to them OR you could ask them to explain it to you one more time. I’ve never used that move before (giving the students who are unsure the option to either practice explaining or receive an explanation), but for whatever reason, it was the right move at the right time. The entire class in pairs and groups erupted into conversation and spent a long time explaining to each other–serious, passionate, intellectual talk with gesturing and smiles. I just stood at the front of the room and watched and waited for the talk to subside. It took a long time. I had a few more clicker questions, which we breezed through. Many groups told me that while they were discussing alone, they had actually spontaneously asked of themselves and discussed the questions I had posed.

I wanted to jot down this brain dump, because I thought the two counter-arguments were really fantastic, and I wanted to think about why this particular talk move worked so well. Part of it is that they were just primed and ready to talk about it more, but I think there was something about putting the power in the hands of the person who doesn’t understand. They were in control-they could demand to hear an explanation or demand that someone listen to them.

Things that are keeping me busy (and away from the blog)

Monthly physics teacher meetings:

Since September, our Department has been hosting a monthly event for local-area physics teachers. We usually have some time at the beginning for demo-sharing on a specific topic area, then we provide dinner and some time to chat, and we usually end the evening by engaging the teachers in some sort of physics/physics teaching activity. So far we’ve had 5 meetings, and we’ve had lots of good feedback from teachers. About 6-20 teachers have been attending. Hoping to continue to nurture this and thread this into some grant proposals.

Learning Assistant Program Pilot:

Last semester, two faculty in our department attended the LA workshop at UC Boulder. This semester we are piloting some curriculum changes and use of learning assistants. Right now, we are only implementing in two section of  our intro physics course and most of our LAs are already physics majors in our physics teaching concentration; but the plan is to implement more widely and to recruit students to be LAs for next academic year We’ve applied for some money that will hopefully help out with that. I’m not teaching in these section, but I have responsibilities for running the prep session with the instructor and the LAs for instruction each week. I have a undergraduate student who is also helping to collect data regarding this pilot implementation.

Two New Preps:

This semester, I’m teaching three courses, but two of those courses are ones I hadn’t taught before at MTSU. The first one is the second semester of the algebra-based physics course, which covers optics, modern physics, and electricity and magnetism. It’s been nice to have a different course to teach, but it’s meant more prep than usual.

I’m also teaching a new course for the first time. We had previously had a one semester seminar course called “Physics Licensure”, which was intended originally to be a self-study-kind of course for future physics teachers to make sure they were prepared for the Physics Praxis. We’ve made that a year long seminar now, in which we focus more on developing conceptual understanding / qualitative reasoning with 1st-year physics topics (and less on praxis prep per se). Students also have responsibilities for working on AP physics problems. This semester is the first time the second-semester of Physics Licensure is being offered. Right now the two courses are still kind of playing the role of “band-aid”, making up for deficiencies in our first-year courses. We are working to improve our intro courses (see above), so the nature of these courses may shift.

On top of this, I’m working on a grant that doesn’t overlap with any of the efforts described above and trying to finish a paper that’s been in the works for years that also doesn’t concern these efforts. The next time I write a grant, It’ll need to be more synergistic with my service and teaching efforts.

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