Second semester physics for us includes topics like waves, optics, electricity and magnetism. With this in mind, I’ve been trying to organize my thinking about how the content is different through a lens that isn’t focused on topics, but rather on the shifts in thinking and skills required.

1. 2nd semester has more and more varied non-linear relationships, including more relationships that have non-monotonic or asymptotic behavior. These include, sinusoidal behavior, exponential behavior, Inverse square laws, and whatever the heck the Thin lens equation is.

2. 2nd semester has more focus on describing how behavior changes over space (potential or fields), whereas first semester has more focus on behavior changing in time. Thinking in wavelengths also becomes crucial. We more strongly employ a landscape metaphor for talking about concepts like potential and potential energy. We shift from vectors to vector fields.

3. 2nd semester has more of a focus on properties of media (index of refraction) and space (permittivity of free space) rather than particles (mass) and objects (density, volume, moment of inertia).

4. 2nd semester has a focus on energy flow (transport) across systems, whereas first semester is more focused on energy transformations within a system. This is reflected in need for concepts like wave speed and intensity. Even how we think about power subtly shifts from the rate of energy changes to rates of energy arrivals and departures.

5. 2nd semester has a focus on local conservation laws, whereas first semester relies more on global conservation. This is a result of focusing on flow.

6. 2nd semester has shifts from single variable functions to multi-variable functions. This is most obvious to me with waves. There also just seem to be more interdependent things going on–circuits.

7. 2nd semester has shift from 1D and 2D geometries to 3D, with examples including spherical waves, Coulomb’s law, magnetic fields and flux. The more complex geometries and focus on behavior over space are at heart of interference. Visualization becomes critical.

8. 2nd semester has a shift in scale requiring more fluency with SI prefixes and scientific notation. Nanometers, TerraHertz, fundamental charge values, etc. I’ve tried over the last year to spend time explicitly getting students to start thinking of SI prefixes as adjectives rather than wholly different units, and to become fluent at using adjectives that allow us to talk in whole numbers as much as possible. 180 mJ, 90 nC, 600 microns, 500 THz,

9. There is a proliferation of new units and unit combinations: Watts (J/s), Coulomb, Volts (J/C), Ampere (C/s), Tesla, Weber, V/m = N/c, eV, Ohms (V/A). Last semester I really noticed how much cognitive demand this placed on students and designed more activities to help us build fluency, familiarity, and connectivity.

10. There’s also a ratcheting up of the instrumentation needed to conduct investigations, diffraction gratings, multi-meters, oscilloscopes, etc.

this is incomplete, but I wanted to start getting a record of some of my thinking.

So, I got distracted from curriculum development, so here are some graphs I was curious about. They were made on my phone using desmos.

Energy vs Time, including total, kinetic, potential, and thermal.

Energy vs Distance Traveled

Mechanical Energy vs Position

Energy vs Position, including total, kinetic, potential, and thermal.

Now With less Damping

Now Critically Damped (this one is not released from rest)

And of course, no damping

1. Be an Advocate for the Field: I have found it important to think of myself as a front-line representative of the entire field of PER, especially research-based teaching and learning of physics. From this perspective, it helps to fill in the gaps of your familiarity with curriculum and instructional strategies that were beyond your range of first contact as a researcher. Maybe you were really familiar with UW Tutorials, or modeling, or ISLE, or SCALE-UP, or PET or learning assistants, or studio physics, or whatever… now you need to be a knowledge resource and even advocate for all of this and more. For me, as a graduate student and postdoc I was more concerned with filling in gaps in my knowledge of research theory and methodology, and it took a fair amount of effort and time to fill in gaps of my knowledge of curriculum. Also as a graduate student, I was trained to be productively critical of physics education research, and to talk in ways that represented that. As an advocate for the entire field, you need to learn to talk as a bit more as an advocate than a critic.
2. Treat your Non-PER colleagues as experts on teaching–whether its the teaching of their courses, or their students, the departmental curriculum, whatever. Proactively seek out their advice, knowledge, and opinions, even if some or a lot of they say disagrees with your little PER heart. They have a wealth of experience and knowledge to draw from, and some of it will be spot on. A lot of what is spot on will be based on experiences you don’t yet have, or on knowledge specific to your setting and students / curriculum. Try out some of the things they suggest. If it works, let them know. If it doesn’t, say, “Hey I tried that thing you suggested, but it didn’t work. Can you tell me more about how you make it work?” Treating them like a trusted, knowledge colleague on teaching makes it much more likely that they will reciprocate.
3. Make Amends when you Act out as a Jerk about Teaching: At some point, likely more than once, you will be a jerk about something education related. When you recognize it, let people know you are sorry and make amends. This can happen in all kinds of ways, and it’s important to recognize when you have trampled on someone for the wrong reasons.
5. Be a Point of Contact for PER Resources: When colleagues finally do come to you for advice on teaching, don’t moralize or pontificate. Instead, be a provider of resources. Be the advocate for the field of PER and point them to resources that you think are closely related to their question, concern, or issue. Let them know that their concerns and questions are important. Share more of your own thinking later if they come back again to talk about, or as follow up.

Hi Everyone,

This blog can now be accessed at teachbrianteach.com (no need for the extra wordpress part). This also means there should be no ads. The old url should still work, so no need to change anything.

This week, a lot of folks on twitter were discussing a paper in Physics Today by Natasha Holmes about the shortcomings of laboratory instruction. I’m not going to specifically get into the details of this paper here, but it was the stimulus for me writing this blog post. It’s a good read, and you should check it out if you haven’t. Anyway, based on my earliest experiences in Physics Education Research, I am not the least bit surprised that it is a typical outcome for most contexts of physics laboratory instruction to have little or no impact on student learning of physics content.

Why am I not surprised? (Spoiler: students can struggle to recall even the outcome of many lab activities, let alone any concepts or principles that relate to those activities.)

Here’s an example from my very first research project while I was a graduate student at Arizona State University. Students in an introductory college physics course would take a traditional laboratory at ASU that was separate from lecture. Each week students collected data (often using vernier equipment) about a different physics topic, plotted various data, and verified that results were consistent with theory. One week after students completed any given lab, I administered a post-test of some sort, related to the topic. What I learned fairly quickly is that you didn’t need to be very tricky with your questions. Often the best ones literally just asked students to state back what they had observed in the lab.

For example, for a lab on projectile motion, students use a photogate to measure the initial speed of a horizontal projectile (rolling off of a lab table), and also use a timing pad to on the floor measure time of flight. Students observed that the time of flight was independent of speed and that the horizontal distance was directly proportional to the initial speed. Students were asked to make plots of this data and also to answer questions

So the next week, the post-test survey I administered asked students to rank the time of flight for three experiments – ones that left the table with speeds v, 2v, and 3v. Some students got a slightly different version of the ranking tasks which was to compare the time of flight for landing at horizontal distances x, 2x, and 3x. The questions included drawings of the situation that basically mimicked their lab experiment. Usually about half of the students could correctly answer such questions after the lab.  (Note: my experience with this data led me eventually to a more careful study of how students were answering these and other similar questions).

Conclusion: If one week later, many students cannot remember the results of these types of labs, we probably don’t stand much of a chance of them learning, remembering, and being able to apply any underlying principles that the lab result was intended to support. Right?

What’s wrong with labs? (Spoiler: It’s not labs per se that matter, but how and whether laboratory activities become relevant objects in broader discourse of students’ learning)

So, the truth is this. I actually do think that laboratory activities can play a supporting role in students’ understanding of concepts, including enhancing students’ ability to transfer those concepts to novel situations. That said, lab activities alone are pretty useless and irrelevant. What matters more is the broader context in which a lab resides, and even furthermore I would say its how students “frame” the role of lab in the broader context of their learning.

So how might I judge whether a laboratory activity I’ve planned is playing a meaningful role in students’ learning? The most crucial thing I look for is what happens in the coming weeks. If we as a class never explicitly mention a lab during ongoing discussions–what we saw, what we concluded, or what it meant– that lab was likely meaningless. That’s it. That’s really my only criteria. I don’t mean the lab was inherently meaningless. I mean that our subsequent activity rendered that lab activity meaningless, retrospectively. In trying to improve things for future courses, it could be that I need to ditch the lab, or it could be I need to better plan for how that lab will be continuously rendered meaningful through subsequent activity, or I need to help with reframing lab.

Lab activities I just do not think have any inherent value, just as activities of mining raw materials has no inherent value outside a broader activity. It’s what happens subsequently in a process that determines it’s value.

Brian, what the heck are you talking about? (Spoiler: here are some examples to help clarify what I mean)

Newton’s 2nd Law Lab: