Undergraduate Physics TAs–I love this class

Here is a reflection from one of the undergraduate TAs enrolled in my teaching and learning seminar.

This week I discovered upon reflection that most of the questions I asked were very convergent. So, what I thought had been a fairly good dialogic conversation, was just a disguised univocal one. Last Friday I also noticed that I tended to have a lot of teacher-student-teacher interactions. So as Wednesday approached I tried to remain conscious of this and aim for more divergent questions and group discussions.

One of the biggest things I did differently was that when I noticed a student seemed unsure of themselves about an answer I’d just tell them to try explaining their reasoning to a random member of the group. This usually easily got discussion going and allowed me to avoid the usual teacher-student-teacher interaction. Other than that I got less timid about posing questions to groups and I found questions I initially found barely worth asking provided more discourse than I thought. This helped to remind me that I have to keep in mind that all of this material is entirely new to these students and trivial questions may very well still be worth asking.

A specific interaction I had in which I tried to engage in dialogic discourse using the questioning technique actually resulted because I was not prepared for the question. It was one of the QODEC multiple choice questions that I had looked over, but not really thought about. So, I initially just asked them to explain why they thought the answer they had picked was correct. After that, we were all still a bit unclear as to which answer would be correct, so I suggested we go through each answer and try to see what it would mean if it were correct. Doing this resulted in most of the members of the group talking to one another about why they thought certain answers were good candidates for the correct answer or not. Eventually, in this way we narrowed the answer down to two questions and I got a bit excited and accidentally gave the answer way. I did not realize that I had done so until I asked them why they chose the answer they did and they responded that thats what I picked. Luckily, this did not get them out of having to justify this answer to themselves before they could bring themselves to actually submit it.

Overall, I found that it was actually a bit of a challenge to listen carefully enough to figure out where students are having problems so I could ask appropriate kinds of questions to help lead them to a discovery. I hope to think more about the questions before this next lecture so that I can perhaps have some anticipated question sets prepared.

I love how this student is able to “sop” up ideas from our readings and discussions and use them as lenses on his own experiences in the classroom. I love how honest and reflective he is about what’s happening around him–what he thinks is going well, and what he’d like to improve, what’s it like for him, and what it’s like for students. I love the fact that he writes about being with student in terms of an inclusive “we”–as in “We were all still unclear as to which answer would be correct”. I love that he is managing to keep his mind on sooo much–discussion, questioning, listening to students, soliciting reasoning, etc. I love how at the end he invents the idea of proximal formative assessment, as a challenge he has faced and wants to pursue as a goal.

Ways of Knowing…

In our physics department, every physics major has to serve as an undergraduate TA. Most of them get assignments in our algebra-based introductory physics course.   Because of the manner in which most of these students were taught (i.e., find an equation and substitute numbers), they can easily find themselves feeling a bit lost in my class, especially if they think they are supposed to be an expert of the content.

For example, here’s a question discussed in class. A bowling ball is dropped from a height of 45m, taking 3 seconds to hit the ground. How fast is it moving the very moment before it hits the ground? The problem is intended to draw out the following answers and arguments, which we hash out.

10 m/s, because all objects fall at the same rate

15 m/s because you can calculate the velocity as 45m/3s = 15 m/s

30 m/s because it gained 10 m/s in each of the 3 seconds

Other more idiosyncratic answers come up as well, but not with high frequency.

The first answer points to the ways in which students haven’t yet teased apart clearly the meaning of acceleration and velocity. The second answer points to the ways in which students haven’t yet teased apart clearly the meaning of average and instantaneous velocity. The third answers is consistent with the idea of constant acceleration. We hear arguments, and counter-arguments, and at some point I help clarify the right reasoning, and what’s both so tempting and subtly wrong about the other answers.

So, here is the way the TA solved it, before class began.

xf = (vf + vi)/2 * t + xi

0 = (vf + 0)/ 2 * 3 + 45

0 = 3/2 v + 45

-45 = 3/2 v

v = – 30 m/s

While the TA could solve this problem, they didn’t have a rich set of ideas for thinking about. It didn’t seem obvious that 30 m/s makes sense, because of the idea that its 10 m/s/s, or because final velocity sould be twice the average velocity (since it accelerated from rest). For other questions without numbers that we discussed, the TA seemed just likely as students to give answers inconsistent with the concept of acceleration. I’m perfectly OK with that, but my suspicion is that the TAs aren’t prepared for this. They aren’t prepared to be wrong about so many things or confused about so many things. I wonder how I can better position them as learners in the class–learners who just know somethings that the first-time students don’t, but not everything.

Of other interesting note is this. In my physics content course for future physics teachers, the students that have had me for a semester or two are pretty rock solid on having a repertoire of ways of think about kinematics problems, and also for avoiding common pitfalls. The others are pretty much falling for all the pitfalls. The difference is pretty striking. The thing that I like is that the range of expertise we have allows for peer-coaching, but also some, “Hey, it’s OK. We were making those exact same mistakes 4 months ago,” and, “Yeah, get used to it. Brian isn’t too into solving problems by putting numbers into equations.”

Blog at WordPress.com.

Up ↑