The pre-class overhead in the physics lecture

This semester, I am a lecture TA in Physics 100, a first year algebra based physics course for students who have not taken Physics 12 in high school. As a lecture TA, I spend my time in the lectures, supporting the students as they tackle worksheets and clicker questions (and sometimes getting to do a fun demonstration!). So far, I am enjoying this post, as it has allowed me to maximize my student contact time (and minimize my time spent marking). Also, it is interesting to see a first-year physics lecture from a different perspective and to think about the approaches being taken and how they compare to the physics education literature. Even though I am not delivering content, this position has brought me closer to the thought process that an instructor must go through while teaching a course. In addition, I have been keeping my eyes open for ways I can contribute to the lecture.

Then, when I saw this post from Peter Newbury, formerly of UBC (now at UCSD), I was intrigued. In it, Peter describes how you can more effectively use the time before the lecture begins by putting something on the overhead to grab the students’ attention. When I mentioned this idea to the professor in whose class I TA, he agreed that it could be great! So, for the rest of the semester, it is my task to find a relevant and interesting image, diagram, video or whatever to put up before class. So far the professor has quite nicely tied these images in with the upcoming lecture, so that at the very least they might help the students transition into ‘physics mode’. I have not been able to suitably observe the students during the pre-lecture time yet in order to see their response to the images.

We have used this strategy at the start of two lectures so far. As both lectures included Newton’s third law, I chose images for which Newton’s third law could fairly easily be applied and that were of things that may be relevant to students at UBC. First, we used an image of a SuperIronMan competitor in the Storm the Wall intramural event at UBC. In this division of this event, the competitor has to scale a 12′ wall with no help. In order to do this, they must use some sort of wall-kick. Newton’s third law is necessary to explain the friction force between the wall and the competitor’s foot that allows them to jump off the wall and reach the top. (A google of ‘UBC Storm the Wall SuperIronMan’ should get you a video of this.)


In the second class, we put up a photo of the Canadian Coast Guard hovercraft Siyay, based out of Richmond, BC. Newton’s third law is important for the hovercraft’s propulsion. The professor was able to insert some ‘wow’ factor for this image: he told of the interesting fact that if a hovercraft such as the Siyay were to run over you in the water, you would be able to come out the other side mostly unharmed. Plus, this photo has a nice rainbow near the front of the hovercraft. (Rainbows are described by physics also, of course!)

Throughout the term, I will be posting the images I choose for the pre-lecture overhead. In addition, I hope to report some anecdotal information as to what the students think of these.

(Image url:



  1. Thrilled to hear you’re adding this pre-class activity – glad my post was helpful.

    I need to do more deliberate observations but I’m finding less conversation when I just put up a picture compared to when I add the “What do you notice? What do you wonder?” prompts. Those prompts also help *me* kick-start the class because it reminds me to find out what the students see, not what I’m seeing for them. People learn by building new knowledge on existing knowledge so it’s critical for the instructor to uncover that existing knowledge…and then build on it. “What do you notice? What do you wonder?” are great probes.

    It would make a terrific little research project for you. Suppose you could get the instructor to always start the class with, say, a 2-minute discussion about the picture. Sometimes you just put up the picture, sometimes you add the notice/wonder prompts. Observe how much the students contribute to the discussion. Do the notice/wonder prompts help them reveal more of their existing understanding? Do they learn to notice/wonder even when you don’t put up the prompts? Lots of cool questions to begin to explore!


    1. Hi Peter!

      Thank you for the good comments. I will bring this up with the instructor and start the discussion about what we could do to help the students bring their previous knowledge into the class through these images and how we can evaluate our efforts.

      One possible difficulty is that this is occurring in a large section of a first-year course (~250 students in a large theatre), so that: 1) It is sometimes hard to get students to volunteer their opinions, and; 2) It is hard to ensure that other students can participate in the discussion between instructor and student. So far, we have tried to have students use a microphone when they comment during the class (this has been a bit of legwork for me, to run the microphone around!) so that everyone can hear clearly. However, using a microphone has a negative effect on 1), in that students are even less likely to volunteer their opinions when they know they have to speak over it. Do you have any thoughts about how to get the discussion going in a large class? Since Halloween is near, one idea I have is to entice students by offering candy for their responses.


      1. Getting students to talk in class, big or small, can certainly be a problem. Candy helps, sure. More importantly, though, the course instructor need to create the atmosphere where the students feel s/he genuinely welcomes their contributions to the discussion. The notice/wonder prompts are great because *everyone* can notice and wonder something and *everyone* can make a contribution. The instructor should thank each volunteer and use the response in a positive way (“Oh, really interesting! I didn’t even notice that!” or “I’m so glad you noticed that – we’re going to be talking about exactly that feature today.”) The instructor can’t pass (negative) judgement on the students’ observations, either in words or body language (Can you imagine the terrible message it sends if the instructor listens and then shows a “WTF?” response!?)

        I think it won’t take long for the instructor to build this vibe in the classroom. Getting the instructor to walk up and down the aisles at first, personally handing out the microphone, asking the student his/her name and then using it, “Thanks, Mary, that’s really interesting.” — that would really help build the relationship between the students and the instructor.

        Oh, and while I’m at it since you mentioned large classes: If the classroom is really large and you have lots of extra space, consider leaving every 5th row of seats *empty* – the instructor and TAs can move up and down these aisles and get within arm’s length of every student in the class. Great for handing out the microphone, listening in on peer instruction conversations, and more.

      2. It’s great to have you joining us in the physics and science education corner of the blogosphere.

        I think it might be challenging to run the study with the queuing phrases vs. not in a single section since there will also be the extra effect of conversations from the previous class. So if you have no queuing phrases one day and you do the next, you wouldn’t be able to tell if it was that they were getting used to having these conversations or if it was the queuing phrase. Testing this between sections is also tough since a given section has a personality all its own, even if taught by the same instructor. But clever people seem to always find a clever way to control for inconveniences in studies!

      3. Thanks for the comment Joss!

        I agree that there are some possible confounding issues here. I haven’t really had the time to think those through, so for this semester, I may settle for observing results from a variety of pre-class media types and different queuing phrases, rather than something more systematic.

  2. […] attached to it, or perhaps some other explanation. As emphasized by Peter Newbury (see comment on this post), one of the most important uses of the pre-class overhead is to connect to students’ […]

  3. […] you recall, I spearheaded the use of the pre-class overhead in Physics 100 last semester. However, for a variety of reasons, most of the instructor’s attempts to instigate a […]

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