Missing the Important Stuff

Bear with me as I force an analogy between watching basketball and grading physics quizzes.

When I watch basketball on TV, especially during March Madness, I’m often annoyed by the way they handle the replays.  After an exciting play, I’ll yell at the TV, begging for a replay so that I can see again exactly how the play developed.  When they do show the replay, I’ll often end up yelling at the TV again, because they left out all the important part of the play.

They show the shot being released, traveling through the air and splashing through the net, ignoring the pick and roll and the deft pass that set up the shot.  The time that the ball is in the air is really the least interesting part of that play.  The ball flies the same way every time, and we already know the result of the play.  Show us how they got there.

Or they show the dunk at the end of a fast break, hiding the defense that set up the break and the smart decicion making of the point guard that got the ball to the right player to finish the play.  The dunk gets the fans excited and shows up on Sports Center, but it doesn’t happen without the key plays that set it up.

Now the switch to physics…

Teaching Journal Week 5 and 6

Once again, a little behind on the update of the teaching journal.  This week’s excuses: tests in E&M and my introductory particle physics class, in addition to grading the first round of lab reports plus the re-writes.  We’re definitely in the thick of the semester now, but at least I have spring break to look forward to in a week.  Of course, I have to make it through my quantum midterm before then, but that’s a different story.

Now, on to the Teaching Journal:

Week 5

Coming up with a good problem for this type of discussion is difficult.  You want to make it doable, but not too simple.  You want to encourage critical thinking, but you have to give the students enough to grasp onto, or they will freeze up, and look to the TA to tell them what to do.  It’s a tough balance.  That’s why I’m glad that writing these problems is not my responsibility.

I bring this up, because the problem for this week straddled a lot of these lines.  The thing that I liked best about it is also the thing that the students hated the most: it was an open-ended problem, with no set answer.  There were many assumptions that the students had to make, and there were several quantities that they could examine to help decide if the situation presented (involving a superhero, naturally) was realistic or not.

I like this type of problem, because it shows how a physicist has to think.  They are not canned problems, with an answer that you can check in the back of the book.  You can’t even look at the title of the chapter to see what concepts might be involved.  It’s just you, your toolbox of concepts and equations, and your creative approach.

The students hate this.  They ask me what assumptions they need to make, what concepts or quantities I want them to look at, or, worst of all, they ask what equations to use.  I tell them as little as I can, but if I’m too mysterious, I get blank looks, and the students just sit there, telling me they don’t get it.  As a result, I end up directing them down a path more than I would like.  The problem with this is that it perpetuates the idea that there’s a certain way to solve the problem that they need to figure out, and the mysterious cues that lead to my approach can remain obscure.

I wonder if these types of problems would go over better with students who are more intersted in physics for its own sake.

Teaching Journal Weeks 3 and 4

I’ve gotten a little behind on these updates.  What can I say, the Jackson E&M problem sets are really starting to get hard.  Plus, this past week, I had to grade 217 quiz problems from the first quiz.  But there’s no rest for the weary in this business…

Don’t forget the latest installment of Adventures of the Learning Assistant over at Morning Coffee Physics.

Week Three

The discussion session for week three was a group quiz.  The students, working in the same groups that they’ve been in for the past two weeks, work on a problem that will count as the first question of their quiz, which they finish in class the next day.  It’s nice for the TAs, since we don’t have to answer any questions or help the students like we normally do, so we can just relax (or work on problems from Jackson).

The group problem was a pretty straightforward problem in kinematics, and most of the groups did pretty well.  I have to admit feeling somewhat of a sense of pride as I eavesdropped on the students while they were working.  The group problem solving and approach to physics problems have come a long way in a fairly brief time.

I began the lab in week three by handing out a sheet describing my general expectations for lab reports and going over it a little bit.  I then strongly hinted that the lab that day would be the lab that they would be writing up for the first paper, so they should do a good job on it.  In general, they’re not supposed to know ahead of time which lab they’re writing up, so that they’ll be forced to take good data for every lab they do, but I figured it would be helpful to give them a little break on the first one.

The lab itself was on the normal force and frictional force, with the standard block-sliding-down-ramp setup.  Unfortunately, this lab came a little earlier than the topic of friction in the lecture, which always throws students off, even if, as a TA, you cover the relevant issues in the pre-lab discussion.

I haven’t graded many of the reports yet, so we’ll see how that goes.  The first lab report is always going to be pretty bad, as the students try to feel out my expectations and develop an understanding for what sort of things should go into a lab report.  That’s why they get to re-write the first one.  Uncertain Principles has some interesting discussion about the role of lab reports in undergrad labs that you should check out.

Teaching Journal, Week 2

Continuing our American/Canadian duality, see Morning Coffee Physics’ Adventures of the Learning Assistant Week 2.

Also, check out Uncertain Principles’ latest installment of his modern physics course report.

Life in the Lab

This week, the second week of classes, was the first week of real labs, consisting of two fairly canonical problems: the falling ball and the cart rolling down a ramp.

Before I got to my first lab, all the TAs for the introductory lab received an email telling us that new video analysis software had been installed on the lab computers.  The old software certainly had its problems; the on-screen instructions were often confusing, and they had a “feature” that made it impossible to go back a step without restarting the lab.  The new software was supposed to fix these problems, among others.

Teaching Journal, Week 1

I am a TA again this semester, teaching the first semester of Physics for Biology and Pre-Medicine, which consists mostly of mechanics.  I decided to start keeping a weekly journal of the experience, how well I feel the students are learning, which things are working well, and what I need to do to improve.

Jasper over at Morning Coffee Physics apparently had the same idea that I had, and the class that he is teaching seems to be along the same lines as mine, so I will link to his posts for an interesting comparison.

Chad at Uncertain Principles is doing a similar thing for his modern physics course, so be sure to check it out for a look at what professors go through when teaching a lecture class.

Background Info:

The class is required for a variety of different majors in biology- and health/medicine-related areas, and is in many ways typical of “physics for pre-meds” classes offered at campuses all around the country.  However, the course is nominally calculus based, unlike many versions of the subject that I am familiar with.  (However, students can get by with very little knowledge of calculus, as most of it is contained in derivations, and even then, it’s mostly simple derivatives.)  Also, the professors make some effort to relate the material more directly to biological problems, even if these efforts sometimes fall flat.  I will comment on these efforts as they come up during the semester.

I teach two sections of 17 students each during a two-hour weekly lab and a one-hour weekly discussion session.  The lab topics cover the standard introductory lab topics, but with somewhat of a twist: the labs are supposed to be collaborative problem solving, rather than strictly canned labs.  This essentially boils down to the students having to decide how many data points they must take to confirm or disprove their prediction.  In addition, we’re not supposed to tell the students exactly the equations that their data are supposed to fit, although later in the last semester, I often broke down and derived the equation for them at the beginning of the lab, and explicitly told the students to check these equations.

The discussion sessions are also collaborative problem solving endeavors.  The groups are given a problem that is intended to be too involved for any of the students to solve individually.  Through collaborations, approximations, and some prodding from their TA, the students are to do their best to solve the problem.  If necessary, I will finish the session by reviewing the key topics the students were supposed to think about, and perhaps sketch a solution to the problem.  About every third week, the problem will be the first question of their quiz, which they will complete on the following day.

Grading the First Quiz

The forecast for rain in the morning followed by sunshine turned into rain in the morning followed by more rain and clouds, so I decided today would be a good day to tackle my first grading assignment as a TA.  The physics for biological sciences class had their first quiz, and I was scheduled to grade one of the four problems.  And after four hours of work, they are all graded, and the grades have been reported.

I’ve gotta say, I’m glad that I graded one of the problems on the first quiz, because I have a feeling that easier problems are easier to grade.  The easiest grades to assign are “perfect” and “zero,” because you usually don’t have to spend much time trying to decipher what the student meant to write, what they were trying to do, how close that is to a correct approach, and finally, how many points that work is worth.  Since this was a pretty straightforward unit conversion, there were lots of perfect responses, which I’m sure greatly reduced the amount of time I spent on the grading.

My method was to quickly go over each paper, sorting them into piles that roughly correspond to grades A-F.  Since there were about 200 papers, this took me about an hour, for an average of about 18 seconds per paper.  The first checkpoint was getting the right numerical answer for both parts (which would have taken me even less time if students knew how to box their answers!  I’m not mad, though.  I’m not bitter).  Students with two right answers go in the A pile, students who only answered one part go in the D or F pile, and I have to look a little more closely to separate the B’s and the C’s.

Allow Me to Re-Introduce Myself…

(Props to those who caught the Jay-Z reference)

So I’ve decided that a few more specific details will make this blog better (at least it will make it more enjoyable for me to write).  Because I wasn’t sure what level of personal detail I was comfortable with revealing, I never really introduced myself properly, I’ll take the opportunity to do so now:

I am a first-year grad student studying physics at the University of Minnesota in the Twin Cities, where I intend to get into high energy theory research.

The University of Minnesota

Thinking Like a Physicist: Super Mario and Problem Solving

My two-week orientation with the physics department began this week.  This program entails some getting acclimated to the program, the department, and the university at large, as well as our first free shot at the qualifying exam (more on that after I finish failing it tomorrow).  However, the bulk of the time will be devoted to learning how to be an effective TA for labs and discussion sessions.  The first part of the TA training has been to think about what the phrases “thinking like a physicist” and “problem solving” mean to us.  In order to help me crystallize some of these thoughts, I have decided to blog about them.

Thinking Like a Physicist

We were told to ask our advisers their opinion on these topics when we met with them to discuss course selections for the upcoming semester.  My adviser had some interesting ideas about “thinking like a physicist.”  The main thing that he said is that he finds learning physics to be more personal than learning math.  By this, he means that physics is done more by feel and concept than symbol manipulation, which he thinks is more emphasized in math.  Because of this personal basis for physics, the instructor is very important, as the students try to emulate him when they set out to solve problems for themselves.  The students must also work to go beyond simply solving the problem and make sure that they can extend the conceptual reach of the problem.

I agree with this idea to a certain extent.  I do believe that a conceptual understanding of the system is the key in understanding a system.  Simple “plugging and chugging” may get you the right answer, but this is useless if you don’t have an idea what this answer means.  This is why physicists often employ the “limiting case” concept: if you can understand how the system behaves as certain parameters get very large or very small, then you go a long way to understanding how the system really works.  I disagree, however, that math is very different in this regard.  My best undergrad math teachers repeatedly emphasized the importance of understanding what was going on by visualization and drawing pictures of the situation, rather than depending on some formulaic “recipe” to spit out the right answer.

How Super Mario Saved the Princess

An important distinction made in our Instructor’s Handbook is the distinction between completing exercises and solving problems.  I think that for my generation, a handy analogy can be drawn to video games.