3rd Lecture, Brownian motion, energy, conservation of energy

I just uploaded my lecture slides to Scribd (see below) and realized (finally) that Scribd was hacking them up, and not providing the pptx files for download. This is a problem. I probably should just upload them to OWW and provide a link to my students. I had in mind that other people may like to "discover" these, but they're so garbled on Scribd that I think people would be turned off. I did notice that Scribd recognizes images from Flickr and Wikipedia and replaces them with the page they came from. That's pretty cool...although in both cases I noticed, I had attributed the images and provided links, so removing them wasn't appropriate, in my opinion. Any thoughts from people on the best way to share lecture slides? 1/31/09 SJK Note: I got advice from J-C and Cameron to use slideshare, so I've switched to that.

OK, now some comments on today's lecture. First, I'll say that I spent a bunch of time learning names before today's lecture. I think I know about 50 out of 150 students, and within a few lectures, I think I can learn most of them (say 120). The first student who asked a question today, I knew his name, and he said, "wow, that's impressive," and I though to myself, "yes...yes it is." Yes I am tooting my own horn. Not because I'm good at learning names (I stink, actually), but because I think it's a really good thing to do in terms of building a classroom community and I'm achieving it. I think it improves the learning atmosphere and students like it. I think also it vastly increases my enjoyment of teaching. One of my talents is to get real happiness out of students' successes. Knowing their names, and even better, knowing a little about them magnifies this effect greatly.

I have no idea at this point whether students liked today's lecture or any part of the course so far. I had assigned them to read Feynman's lecture about conservation of energy, which I love. I asked them via show of hands who found the reading (like 4 pages) illuminating, and NONE of the >120 people raised their hand! Ouch! That's really good to know, of course. I made the common mistake of putting the students way out of their context of understanding. I love the Feynman piece, but I've been through graduate school in physics. This is many of these students' first science course in college. The irony is that during my first lecture, I led them through that fantastic exercise (Wason selection task), which demonstrates how important context is. Whoops & sorry! I'm not too worried, though, as I am pretty confident that the upcoming topics are going to be pretty interesting and illuminating.

The big demo today was the nose basher. This is the one where there is a bowling ball hung from a hinge on the 20 foot ceiling. The unlucky person (me in this case) holds the bowling ball up against his face, let's it swing down and away, and back again. Of course, it does not bash his face (but please supply youtube videos if you know of other results). But the ball moves remarkably fast when it is mere feet from the face. It's alarming. And quite crowd-pleasing. The demo actually doesn't prove anything per se. But it's so entertaining that I think it's a great backdrop for talking about conservation of energy and energy flow. A student, Brandy, even pointed out that the ball was like an inch from my face, not exactly touching it on the return. This was a great way to point out transfer of energy to the air.

The other demo is the "rattleback," the asymmetric wooden thingy that only likes to spin in one direction. We have a big one that's easy to see. It's a great toy, just fun to observe. And like Nose Basher, it's a good backdrop for discussing energy flow...as well as the fact that conservation of energy doesn't let you predict everything about energy flow. I first saw this demo when a famous physicist gave a keynote lecture at Cornell in 1997 or so. He named the rattleback as one of his 7 wonders of the world. Another of his was the "green flash." I don't remember the other five, but they too have probably been solved in the post-wikipedia age :) I remember liking the rattleback, because I had previously noticed it with many telephone handsets (they exhibit the spin / rocking reversal). I tell my physics 102 students what telephone handsets are and explain to them the concept of the "home phone."

Next up on Thursday, we start talking about waves. Two key demos. First is the "wave table." This is such a beautiful demo device. It makes wonderful waves. If I had one of these in my house or office, I would probably spend 5 hours a day waving it. The second is the Ripple Tank applet from Paul Falstad. It's a fantastic applet for demonstrating countless wave phenomena.

03 Brownian And Energy After Class

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First lecture in conceptual physics course, Wason selection task was effective

Yesterday I presented my first lecture of the semester in Physics 102, "Introduction to Physics." The alternate course title I like best would be "Conceptual Physics," and others are "Physics without Math," "Physics for Poets," "Why the Sky is Blue," etc. You can find my syllabus on Scribd. Here are the goals stated in the syllabus:

The primary goal of the course is to help students develop a better understanding of a variety of physics concepts that they experience or hear about in their every day lives. We will strive for true understanding of the concept versus tiresome memorization of facts and trivia. This may lead to a heightened enjoyment of everyday physics wonders (such as rainbows, sunsets, waves, phases of the moon), improved ability to understand technological issues (such as energy shortages and sources, nuclear power and radiation, cell phone communication), and a deeper understanding of future scientific material including biology, chemistry, geology, medicine, and possibly a subsequent more advanced physics course!

I like these goals, but they are not measurable, really. I did not take the time this semester to implement pre-testing and post-testing assessment as I had hoped. Perhaps partially the reason I didn't is I'm still quite annoyed that this is the last time I'm going to teach this class for a number of years. Our department has a custom of switching courses every 3 years, and also I was told that I need to show diversity in teaching in order to get tenure. I strongly disagree with both of these notions, but well, you know...

In any case, the goals are to have fun learning some physics concepts and to come away from the course with a positive impression of physics and science and an ability to enjoy learning about them. I don't have rigorous data, just informal student feedback (thank you emails, which I absolutely love to receive) and the scantron feedback forms. But this anectdotal evidence indicates that our goals were achieved the first two years. Plus, I have really enjoyed it and felt good that many students learned a lot and enjoyed the course. The only negative is that it takes a lot of time, especially the first semester I taught the course, where I developed about 28 powrepoint lectures from scratch, 75 minutes each--that utterly kicked my ass. I would like to put all of my powerpoint lectures on Scribd, in case they could ever be useful to someone else. The only thing keeping me from doing this is that I know I've missed attribution of some of the pictures I've "borrowed" for my lectures. Plus, I definitely don't have copyright on many of the non-CC licensed images I've used. Any comments on how to deal with this? I have in mind that I could try to correct this as I present the lectures this term, but realistically, that's not going to happen.

I did post my yesterday's introduction slides on Slideshare. I think the only stuff I use is from wikipedia and I attribute it. Overall, the lecture went well and I had a great time. Once again, the students are fantastic and I am sure I will enjoy getting to know them and seeing them succeed. I have some comments on a couple specific things from yesterday.

Wason Selection Task

One thing I do during my first lecture is take pictures of all of the students while they are doing group discussion. This accomplishes a number of things. First, it gets them acquainted to talking with their neighbors, which we do several times / lecture. Second, it allows me to practice learning names over the next couple weeks. I have each group write down their names along with physical description and then I go around the room taking photos of the group and telling them their group number. It will take me a couple hours to put the names with the faces in powerpoint, and then a couple more hours of studying. Combined with interacting with the students, I've been able to learn quite a few of their names. I did pretty well with 120 students last year, but this semester I have 154 students registered, so I'm nervous whether I'll be able to do this or not. I think it's important, though, and the ability to talk to people by name adds a lot of value for students. Incidentally, I'm helped by the fact that students tend to sit in the same areas every day, so I'm basically making a seating chart without imposing one. This is a technique I learned from TA training, and it works really well. Thank you to whoever did TA training at Cornell Physics in 1996!

OK, so in order to carry out this exercise on the first day, I need an entertaining puzzle for the students to debate with each other. The first two years, I tried using the Monty Hall paradox. That worked pretty well, but this year I switched to the Wason selection task. I was REALLY happy with the way this turned out. First, I had them use their iClickers with the number / color version of the selection task. Since most of them did not yet have iClickers, I also had them shout out their answers (surprisingly, it's pretty easy to poll 150 students this way, and the shouts matched the iClicker graphs). Most people got the puzzle wrong (which is what always happens), and after debating, a consensus developed on the "wrong" answer (to flip over all the cards). The reason I liked this puzzle so much is because when I showed the same logic puzzle with the beer / under 21 version, then entire class immediately picked the correct answer. I could then show the two questions next to each other and blab some stuff about how learning is contextual. I think it does demonstrate that, but the important thing is that they probably had fun while I took photos and probably remembered the exercise in a positive light and some probably even tried it out on their friends after class. I'll definitely use this for my next large class.

Wireless in the classroom

Someone on friendfeed recently posted an article talking about either the perils or opportunities of wireless in the classroom. It turns out my classroom has wireless for the first time, so I brought this issue up with the students. I basically told them I was worried about the possible distraction, but that the worry was far outweighed by the possible benefits it could have. I was telling them I didn't really know how we'd leverage it, but that I encouraged people to use it. While saying this, I saw a Mac laptop in front of someone, so I said, "Like you, Mac Guy (I don't know their names yet)...you're probably already checking out our facebook page, aren't you?" He said, "Yeah! actually I am...I'm looking at photos of you." (At this point I realized that there must be a bunch of embarrassing photos of me on facebook.) I said, "like what?" and he said, "Some marching band photos..." I made a perfect dramatic pause and then addressed the class, "Well...you already knew I was a dork." This drew much laughter, which made me happy. OK, that little anecdote was unnecessary, but it was funny if you were there. This wireless experiment will be interesting throughout the semester. The one thing I have in mind is that we look at a lot of applets during lecture, and I'm hoping the students will be trying them out themselves while I'm showing it on the projector. I can see that this could turn into mayhem, but I also feel that the level of learning will be much higher if they can play with the applet themselves. We'll see!

Tomorrow we'll do the first real physics lecture, where we'll talk about the structure of matter, focused around Brownian motion. The two demos will be a demo that shakes ball bearings on an overhead projector (to give an idea of molecules in a gas) and a demo where we look at laser speckle off wet and dry paint. This latter demo is really cool and easy to do, and I find it a fascinating demonstration of Brownian motion without need for a microscope. I learned it from Dan Ralph during his graduate solid state physics course at Cornell back in 1997-ish. You'll need to see it with your own eyes (maybe I can take a video of it?), but the laser speckle pattern on dry paint does not change if you keep your head still. On wet paint, the pattern shimmers, due to the microscopic latex particles undergoing Brownian motion. So, basically you can see evidence of Brownian motion with a cheap laser and paint. Laser speckle is a great demo, because you can see it from any distance away, and it's fun to look at whether or not it's shimmering.

01 Course Intro, Administrative, Etc After Class

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