At upcoming Physics Education Research Conference in D.C., I am giving a talk and also moderating a poster symposium. In preparing for these, I wanted to spend some time writing about related things. The talk I am giving and the session I am moderating are the following:
Is there room for wonderful student ideas within the canon of introductory physics?
Introductory physics courses often come with constraints that make them less than the ideal setting for responsive teaching efforts that aim to support students in having wonderful ideas of their own. In this talk, I present cases of students having wonderful ideas in introductory physics courses for the purpose of providing rich illustrations of how wonderful ideas may emerge when parts of the canon are opened up for student sense-making. I follow up with a discussion of how such moments benefit from careful instructional planning and curriculum design that are aimed at supporting both traditional and non-traditional outcomes.
Identifying Conceptual Resources for Understanding Physics:
Historically, research identifying student ideas in physics has focused on what student misunderstandings, misconceptions, or difficulties. This work has supported the development of curriculum that elicits and addresses these misunderstandings and has informed instructors’ knowledge of student ideas. More recently, research has begun to systematically identify student conceptual resources for understanding physics — that is, the productive “beginnings” of physics that students bring to bear as they learn. This session showcases some of this research, highlighting a range of samples (K-12 students, university students, and teacher-learners) and physics topics (thermal physics, energy, electricity and magnetism, and pressure).
I. Background on a N2nd Law Lesson
So, here is a question that has been a favorite of mine the past few years:
The question by itself isn’t all that amazing, but the timing of the question in our curriclulum seems to make for a good conversation, so it’s relevant to know the background.
First: by the time I am asking this question to students, they will have spent a lot of time with velocity-vs-time graphs– they are embedded into many exercises, clicker questions, card sorting tasks, example problems, quantitative problems, and lab activities. All students would have some familiarity, most students would be al least proficient, and some quite adept.
Second: This question comes at the end of day focused on helping to define and investigate what forces are–with careful attention to the mechanisms by which various contact forces arise.
II. Student Thought Experiment
Within this context, the students in my class one semester discussed the above question and over a period of time ended up convincing each other that the only reasonable outcome was for the hover puck to continually speed up.
The persuasive argument–initially provided by a single student– eventually was taken up broadly. The argument was essentially this:
1st: When you press your finger against the hover puck, it’s going to have to speed up a bit as it to starts to move.
2nd: In doing so, however, the hover puck gets away from you;
3rd: As the puck gets away from you (even just a little bit), the amount of pressure against the puck goes down. Your finger isn’t as squished into it as much.
4th: Thus, in order to maintain the same amount of pressure, you have to speed up with the puck. You have to keep up in order keep the same level of squish.
5th: Once you are moving along with the puck again and you are again pressing into; the puck again tries to get away, speeding away from you.
6th: So, as long as you keep pressing against the puck (and don’t let it get away from you), the puck is going to just keep speeding up (because you keep pressing into it).
7th: Of course, this will be hard to do, because you are going to have keep speeding up with the puck to maintain the pressure, but if you can keep the pressure up, the puck will keep on speeding.
In class, the argument was never so cleanly articulated, but I do remember the first words that uttered by this student a few minutes into the discussion. The argument developed and became elaborated progressively over a period of at least 20 minutes, with lots of people adding on, giving examples, and counter examples, and clarifying what was meant. ” By the end, the feeling in the room was almost: “It’s so obvious that this is what will happen, we don’t even need to the do the experiment.”
Of course, we still did the experiment, but the reason for doing the experiment was NOT so much to see if it “does continually speed up”, but rather to investigate the more pointed questions and claims that had arisen about why, such as
- “Does it seem like the puck tries to get away from you? When this happens, does it seem to lessen the pressure?”,
- “How hard was it to maintain constant pressure? Did you have to keep speeding up to maintain that pressure?”
- “What happened when you couldn’t keep up and lost pressure against the puck? How was that different than when you were able to maintain pressure?”
We ended up doing these experiments out in the hallway with hover pucks, and then again more carefully in the classroom with fan carts and motion detectors. The fan cart was introduced basically as a technique for maintaining a more steady pressure –> the argument being that the cart can’t get away from the fan (or the air). That is the fan could do a better job of keeping the pressure constant. This is what allowed us to decide that the answer was A (constant force –> constant acceleration).
III. Why Tell this Story Again?
It’s true that I’ve written about this specific class discussion before, but I’ve been wanting to return to it again, because it’s a story with lots of interesting aspects that has stuck with me.
First, it’s important to note what the question did NOT ask. The question did not say, “A constant force acts on an object…” Instead, by keeping the focus on constant pressure (here meant in our class informally as a degree of squish), it helped students to attend to that aspect of the mechanism. This was additionally supported due to fact that we had spent entire day looking at the details of these types of interactions. Generally, however, students’ concept of “force” could more easily anchor to other aspects of the motion–> for example it would be common for students to attach constancy to some other aspect like the “speed of the pushing” is constant or the “effort of the pushing” is constant. rather than the constancy pertaining to a degree of squish between the finger and puck.
Second, my previous experience, with physics education and my own teaching, had always been more focused on using these conversations as more of a lead into to getting students to meaningfully consider the observations. That is, the conversation guides students to think about what they think, make a prediction, and then see how the observations compare to what they thought. Lots of good research to support the notion that this type of prior engagement with the ideas (predicting and discussing) is critical to creating the conditions in which students will actually be able to understand and learn from such observations. Here, however, students did not arrive at the conclusion that “constant push causes endless speeding up” through direct observation, but rather through thought-experiment. This is more akin to the kinds of reasoning we liken to scientist such as Galileo and Einstein.
Taken together, this kind of learning is a glimpse of the kind of teaching that I was apprenticed into while at the University of Maryland–one that aims to value helping students to build on and refine their own “sense of mechanism“, to “shop for ideas” in their experience, and to engage in a process of seeking out “coherent explanations” for phenomena. To a significant degree, for me and others, this kind of teaching has been easier to take up in courses that live outside the standard introductory physics course sequence and are perhaps less tethered to the canon of introductory (see here, for example). It is certainly more challenging in many contexts where pace and content can pull you more strongly away from commitments to teaching in this manner (and supporting learning in this manner).
IV. How does this connect with PERC Sessions?
My talk at PERC will be on the topic of to what extent this kind of teaching / learning can find space in the standard introductory curriculum–where students are supported in having and developing scientific ideas that are not precisely predetermined. While in this lesson, I planned for and knew that we would be making progress toward learning Newton’s 2nd law, I did not know in advance that the specific understanding that would emerged would be built around ideas like “pressing against something leads to it trying to get away” and “getting away involves both speeding up and a lessening of pressure”.
These specific student ideas are (I think) the types of ideas that are the focus on the Symposium I am moderating– researchers whose goal is to identify ideas that students have that can serve as “resources” for making progress in learning specific scientific ideas (rather than, for example, researchers whose goal might be to identify misconceptions or student difficulties). One of the challenges I see for these researchers doing the work is to meaningfully situate the resources they identify in ways that give them “life” such that teachers can see their continuity with the actual practice of teaching. In the story above about my students, I would hope that readers get a feel for what these students ideas actually were and how these ideas actually served as resources for making progress in learning Newton’s 2nd law. Pivoting from the Symposium to my own talk, my talk will focus on how such moments of teaching and learning benefit from instructional planning and preparation (even if you necessarily cannot prepare and plan for some of the details of what exactly is the form of students’ understanding will that emerge).