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.

Labs Week 1

The first week of lab has a lot of preliminary boring stuff that nevertheless has to be done: introducing myself to the class, overview of expectations and grading, etc.  We also have to allot about 45 minutes for the students to take the Force Concept Inventory (conceptual questions about mechanics designed to expose common misconceptions) and the CLASS attitude survey.  The results of these tests are then repeated at the end of the semester, and the data are used by our physics education research group.

This leaves about 45 minutes for some real lab work.  We decided to use this time to introduce the students to the video capture and analysis software that is used in the majority of the labs we will do this semester.  For a simple example, we had the students video a cart moving at constant velocity.  They then step through the frames, marking the location of the cart at each time step.  For the positions and velocities in both directions, the students predict the graph of the data, and then, after collecting the data, they fit the data.

Besides simple familiarity with the software, there are several key concepts to get the students to understand.  The first of these is the calibration of the dimensions in the video.  The students must enter the length of an object on the screen to set the scale for the video.  Many of my students last semester never really understood what this step was about, and I blame this on my poor explanation and assumption that the students would readily grasp the concept.

The other key concept is the error inherent in using this program.  Error analysis is not a major focus of this course, but it still must be addressed.  In particular, small errors in marking the position become bing errors in the velocity, since each frame is separated by 1/30 of a second.  Understanding this will help the students explain their errors and also prevent them (by not taking data on every single frame).

I think that most of the groups figured out what they were doing, but, of course, time will tell how good their understanding is.

Discussion Week 1

The goal of the first discussion was mostly to give the students a taste of how these sessions will go, with the actual physics contained in the problem secondary (in my opinion).  Last semester, for a variety of reasons, I don’t think the atmosphere in my discussions was very conducive to real discussion and collaboration, and I am determined to improve this for this semester.

My first step for doing this is to make sure that the desks in the room are positioned into groups when the students arrive, shifting the focus from me and the chalkboard to their groups and their own solutions to the problem.

Secondly, I wanted to “stir the pot” a little, get the students talking, and try to drop the inhibitions a little bit.  So I had the students play a little icebreaker game within their groups, where they made three statements about themselves, one of them being false, and the other members of the group have to guess the lie.  It’s a little corny, true, but they had to get talking, which was the point.  Besides, who’s going to complain about having to play a game in class?

The actual problem was a good one to start with, because it required the students to make and state assumptions, make estimations, and think about units and scaling.  I was impressed that most of the groups got right to the business of brainstorming and talking about their approach and assumptions.  A few groups needed prodding at the beginning, but eventually got off the ground.

A key thing that they have to learn is to just throw out ideas and try them if they sound reasonable.  On a difficult and involved problem, you’re not going to come up with a fully formed plan of attack from the get-go, and execute it flawlessly from there.  You’ve just gotta throw some stuff at the wall and see if it sticks.


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