# Days 61-63: Energy Bar Charts & Newton’s 2nd Law

This was supposed to be a four-day week, but an impending winter storm means we will be starting our winter break a day early.

AP Physics 1: Energy Bar Charts

This week I introduced students to energy bar charts and we spent a lot of time working and whiteboarding problems. Since we had two rounds of whiteboarding in a 3-day week, I asked students if they wanted to change it up from mistakes whiteboarding, but they were adamant that mistakes whiteboarding helps them learn. I was more concerned about whether they would be up for engaging in that much mistakes whiteboarding than whether it would be useful, so happily went along. I am really glad that they are seeing the value in making, analyzing, and discussing mistakes for their learning. I also had some great conversations with students this week where they talked about the growth they feel like they are making in this class, which is fantastic. That is a great note to go into winter break on.

Physics: Newton’s 2nd Law

This week felt more awkward with this course. We had a quiz on Monday that had been pushed from last week due to a snow day. Then the plan was to start the lab we’ll be doing on Newton’s 2nd Law. We are planning to use the motion encoder tracks, but students haven’t had any hands-on experience with them yet and haven’t used any velocity vs. time graphs in a few weeks. To address those issues, I put together an activity where students reviewed position vs. time and velocity vs. time graphs using the motion encoder tracks. That seemed to really help students feel comfortable with the equipment and set up what they’ll need to remember to find acceleration in the lab. That left us with today to start the lab. I dragged my feet on the introductory discussion rather than starting data collection, then picking it back up after two weeks off. We’ll see what I think of that decision when we come back from break!

# Days 27-31: Balanced Force Practical & Newton’s 2nd Law Model-Building

This week we wrapped up balanced forces with a practical. I used some magnetic hooks to attach spring scales to the whiteboard and let students measure the forces and any angles they wanted. Even though I only had two setups and five groups, different groups ended up taking different approaches, which was great for students to see in some discussion after the practical. We also had some good discussion about uncertainty when we measured the actual mass and students were initially disappointed with how far their calculations were off before, which lead to the realization they’d actually been pretty on target!

After the practical, we started Newton’s 2nd Law with a paradigm lab using the standard modified Atwood’s machine. There was some messiness in the value of the slope that students got, which is pretty typical from when I’ve done this lab. One of these days I’ll figure out how to coach students to really high-quality results! Students did really well at translating the equations for their line of best fit into something that had units and variables that matched the experiment and did a nice job in the board meeting making sense of their slope and intercept.

# Days 24-26: Force Diagrams

This week was only 3 days due to the state union conference held this week.

This week we started working some balanced force problems using vector addition diagrams. I noticed my students were struggling with getting the interaction diagrams and free-body diagrams correct, which then made the rest of the problem trickier. In the middle of the week, we stepped back from the problems to really dig into setting up the interaction diagrams, free-body diagrams, and vector addition diagrams on whiteboards for a range of situations with the hover puck. We got to revisit some important ideas, like the idea that forces must be an interaction, and dig into some things that didn’t come up on previous problems, like how whether you include something like the air cushion under the puck as part of your system can change your diagrams. This day seemed to really help students see the value of some of the thinking I’ve been asking for and to feel more confident in drawing and using these diagrams, which is just what they needed!

# Days 15-19: Building a Force Model

This week was all about starting to build a model of forces. We started by tapping bowling balls with mallets, using a version of the activity based on Frank Noschese’s. Students were quicker than usual to recognize that they had to juts leave the bowling ball alone once it was moving to keep it moving at a constant speed, but I still pulled up an old image I made with motion shot to get some additional evidence. After that, we moved into a version of interaction stations from Kelly O’Shea where students identified forces based on stretch, compression, and shear. Finally, we wrapped up the week with some mistakes whiteboarding with force diagrams. When I introduced system schema and free-body diagrams, I didn’t emphasize enough that the free-body diagram only needs to show forces that cross the system boundary, but that lead to some great conversations during the whiteboarding as students figured out what they needed to include. One student commented that almost all of their mistakes related to including more than they needed to, which lead to some nice discussion about the fact that the hardest part of physics is often figuring out what is relevant.

# Days 10-14: Building CAPM

This week, students did a lab with ramps to start building the constant acceleration of a particle model. Students used Vernier Video Analysis to get their graphs, and I really love how the video analysis tracks set up motion maps for constant acceleration. Students seemed to feel pretty good about some of the math-y skills in this lab, including linearization and “translating” their line of best fit into a version that has variables that match the experiment and units on the slope and intercept. We then did some mistakes whiteboarding with problems translating between different representations of constant acceleration, which my students continued to do fantastic with.

One thing I think is worth thinking about it it feels like because this is our first experience with linearization, the later days of this lab feel very focused on the math. Then, it feels like we set the heavy math aside while working on translating between representations, only to circle back once we are ready to start doing problems. I wonder if there is a way to structure the constant acceleration unit differently to make it feel more coherent. We have the Vernier motion encoder carts, so I wonder if one option could be to start by having students more or less play with carts on ramps to focus on the shape of graphs, then work on translating representations. Then once students are solid on the representations, do the more standard ramp lab to bring in mathematical representations.

# Days 5-9: Deploying CVPM

This week was all about using the constant velocity of a particle model. We started with some problems translating between different representations that we went over using mistakes whiteboarding. Last year, I had some classes where it helped to do a gallery walk before the whole class discussion, so I decided to try that from the start this year. This class did a great job with the gallery walk and every student was able to say something about every whiteboard. They also did a great job during the whole class discussion. There was one whiteboard that sparked some great student-to-student talk where I could hear students getting a better understanding of motion maps as they talked.

We wrapped up the week by predicting where two buggies would collide. I told students there was a range of possible approaches, and one group took that as a challenge to find as many different approaches as they could. A homecoming pepfest on Friday meant we ran short on time to have students share how they approached the practical, but I want to make sure and revisit that next week.

I also set aside some time this week to work on good collaboration. That is something I was not very consistent about last year, and I think it contributed to how much some students struggled in groups. We spent some time discussing the different kinds of contributions that were useful this week to ensure students are seeing a variety of ways they can be good at physics. Next well, I’m planning to introduce group roles.

# Days 157-161: Pendulums & AP Review

Physics: Pendulums

We spent most of the week on the pendulum lab exploring the variables that affect the period of a pendulum. This will be our last model-building lab for the year, so it was good to see students figuring out plans for data collection and getting high-quality data with minimal intervention from me. Connecting the data to a mathematical model was still tricky for students, but they worked through the challenging parts to figure out what was going on. They really hated the unit on the slope of their period vs. square root of length graph (I don’t blame them!), but I was able to use that as motivation to try and get a nicer unit by rearranging things so that we had the length divided by a number in m/s2. From there, students were quick to suggest that the slope has something to do with gravity. From there, I showed that the value happened to work out if we put a 2π out front. This approach could use some refining, and I’d especially like to put more of the thinking on students, but students did seem clearer on the significance of the slopes of their lines than in the past.

AP Physics 1: Review

With the AP exam on Thursday, the first three days of this week we focused on review. My students this year really liked Plickers for multiple choice and had some great discussions, when whole class discussions have generally be tough this year. I wonder if I should have pulled out Plickers earlier in the year as a way to get them talking and to build up to some other types of class discussions.

I had a brainstorm for a review activity, that unfortunately came the day of the AP exam, so too late to try. I do a lot of having students start by just looking at the diagram and scenario description, then deciding what models seem useful and sketching some diagrams. It crossed my mind this could lend itself to a card sort, so I put one together with the released free response to date. I haven’t tried it with students, but I think I would start by having students match each prompt to at least one of our models, then give each group a problem to sketch some diagrams and brainstorm what they could figure out.

# Days 147-151: Free Fall Practicals & AP Review

Physics: Projectile Practicals

It’s been tough for students to make connections between labs, diagrams, and mathematical representations this year, so I was nervous about the shift this week from sketching diagrams for projectile motion to doing problems. I had a brainstorm on my way to work for scaffolding that transition that worked out really well. First, we did a lab practical where each group got a strip of clear acrylic and a random time. They were tasked with calculating how far apart they should place pieces of tape so they could get a photogate to read their time. That meant students only had to think about the vertical motion, which seemed to help with connecting measurements, diagrams, and mathematical representations.

The next day, I wanted them to think about motion in both directions, but keep the distinction between those two directions very concrete. We tried a lab practical I’ve seen where each group got a random distance for a constant speed buggy to travel, then had to calculate where to drop a marble from so it would land in the buggy. The two separate objects seemed to help students wrap their heads around what we mean by the vertical motion and what we mean by the horizontal motion and why the time must be the same for both.

At this point, we talked a little about how thinking about the motion of the buggy and the motion of the falling marble simultaneously was similar to thinking about the motion of a projectile. Students seemed to make that connection really nicely. One benefit I hadn’t thought about in advance is they also seemed more confident starting the problems, having already had multiple, tangible successes with this kind of thinking. This seems like it could be an argument for putting lab practicals or similar experiences early in a unit, rather than only toward the end where we tend to use them.

AP Physics 1: AP Review

We wrapped up angular momentum and started reviewing for the AP exam. We spent some time on model summaries, where students revisited the diagrams and equations central to each major model we’ve used this year. The next day, I handed out the 2021 free response and we took some time to just read the problems and talk about things the students noticed. Next, I gave students the scoring guide and we made some observations. Finally, I handed out the student samples that are publicly available to make more observations. This lead to some good discussion about what the readers are looking for as well as some good conversation about strategy, like how to make use of diagrams or the importance of taking the time to break apart the text.

# Days 110-112: Energy Pie Charts & Pendulum Practical

With President’s Day on Monday and a PD day on Friday, we had a 3-day week.

Physics: Energy Pie Charts

This week we did mistakes whiteboarding with energy pie charts. There was some great discussion, both as students prepared and as they presented the whiteboards, that came from students working through what differences represented someone making a mistake vs. what differences represented different, but equally valid choices.

We also briefly revisited momentum transfer this week. On the last quiz, I saw a lot of evidence that students were struggling to connect the equations and math for conservation of momentum to their momentum bar charts, which fits with a larger pattern I’ve seen this year of students struggling to connect different representations. As we get into conservation of energy at the start of next tri, I need to give a lot of thought into how I’m going to support students in making connections between mathematical and graphical representations. I do a lot of card sorts to try and help with these connections, but I think I might need to plan some discussion that specifically focuses on how the mathematical representations relate to the diagrams.

AP Physics: Pendulum Practical

This week, we wrapped up pendulums. My students could use more practice and feedback on designing experiments and writing procedures, so I decided a pendulum practical would be a good opportunity to practice this. I tasked students with finding the length of a string without using a meterstick or ruler. Before they could get their string, they had to write out their procedure on a whiteboard and get it approved by me. I think this would have been tough to manage in a large class, but I currently only have 11 students in AP, so was able to pretty easily take time to give groups meaningful feedback and check their revisions before cutting them a piece of string to use.

# Days 90-94: Impulse Problems & Energy Practical

This week we were back in-person after two weeks online.

Physics: Impulse Problems

A big theme I saw across my classes is that students had a pretty decent grasp of impulse, but didn’t think they had learned much the last two weeks. I kept thinking about my PhD research so far where, in some data I collected pre-pandemic, I found that even when students were mastering the material, they struggled to build confidence and self-efficacy from activities that were purely computer-based. In addition, right before we went online, my students also made clear that they really value discussion and collaboration as a way to learn physics, but I struggled to get students talking to each other online. With those things in mind, this week was all about giving students space and time for discussion and collaboration to build their confidence. We spent a lot of time whiteboarding various problems, including some that were assigned while we were online, so that students could talk to each other. I also gave much more feedback than usual while students were working on whiteboards to point out what they had correct or what they were doing well, which seemed to really help students see just how much they had learned the past two weeks.

AP Physics: Energy Practical

My students have been feeling pretty good about doing problems with conservation of energy, I think in part because we were able to start them in-person, then do a lot of practice while we were online. I wanted to give students something hands-on before we wrap up energy, so I got out the popper hopper toys and tasked students with finding the spring constant. To help my students with writing procedures, I had each group write a procedure on a whiteboard, then give it to another group to follow. They were allowed to go ask the group who’d written the procedure questions to clarify steps or discuss changes as both as a way to give feedback to the group who wrote the procedure and to ensure that every group was able to complete the task, even if there were issues with the procedure they were given. I think that helped give students a concrete target for what needs to be in a procedure.