Days 167-170: Pendulum Practicals & Final Project

This was the last week of school for seniors! Since they are around 90% of my students, this was the last week of instruction in my classes. Next week, the juniors in my classes will have time to finish anything they still need to for my class or prepare for finals in their other classes.

Physics: Pendulum Practicals

This week we did two lab practicals using pendulums. First, we had students determine the length of a pendulum using only a stopwatch, which went really smoothly. Next, we had students figure out where to start a buggy so that the pendulum bob would collide with a passenger in the buggy. The big thing I noticed was students treating the period of a pendulum as three different equations, depending on which variable they were solving for. This fit with a general pattern this year of students struggling with using math in physics. While I think the unique challenges of last year are a factor, I think it would also be worth looking at our curriculum to see how we could do a better job of not just using math, but helping students develop a conceptual understanding of the math we are using. I won’t be able to work on that directly next year since I will be out of the classroom working as a high school science content specialist, but I’d like to think about how I can support teachers interested in that work. There will also be a high school math content specialist, and I think it will be worth having some conversations with him to think about how our departments could collaborate.

AP Physics 1: Final Projects

Students met with me about their final project drafts, then presented them to the class. I feel like while these students are phenomenal in small groups, I’ve struggled to build a whole-class community this year. During the presentations, however, there was a lot of joking around from both presenters and the audience, and several presentations included references to Throckmorton, who appears in many of our problems. I think we had more of a whole-class community this year than I realized, it just looked different than in previous years. It was really nice to have that so apparent on our last day together.

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 152-156: Projectiles & AP Review

Physics: Projectiles

This week was a little hairy since students were in and out for AP exams. We continued working on using velocity vs. time graphs to quantitatively describe the motion of projectiles. We wrapped up the week with a practical to predict how far from the edge of the table a marble will land. I spent more time than usual working on breaking up the three phases of motion (constant acceleration while the marble is on the ramp, constant velocity while it rolls across the table, and projectile motion once it leaves the table), but it was still pretty challenging for students to connect when to use the measurements they made in their calculations. Based on the conversations I had with students, I think this fits in with a larger pattern I’ve seen this year with students struggling to connect labs to mathematical and graphical representations. As we move into the last few weeks of the school year, I want to make sure I keep thinking about how to support students in seeing the mathematical and graphical representations as meaningful descriptions of something physical.

AP Physics 1: AP Review

We continued reviewing for the AP exam. I didn’t do anything particularly interesting. We started each day doing a few multiple choice questions on Plickers, then moved into working some released free response. For the free response, I let students pick problems to work on based on the topics they want to work on reviewing. With both the multiple choice and the free response, I made sure we spent some time discussing what the problems illustrate about the type of things that tend to show up on the exam, things that tend to show up on the scoring guide, and strategies for approaching the question. A lot of my students have resisted using the formula sheet this year, and it’s been good to see students getting more comfortable referring to it this week and even using formulas to figure out the significance of the slope and area of graphs they are rusty on.

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 138-141: Popper Hoppers & Unbalanced Torque

We had Friday off this week. I think staff and students alike were very happy to have a long weekend.

Physics: Popper Hoppers

This week we wrapped up energy. After finishing the bouncy ball evidence-based reasoning from last week, we got out the popper hoppers to use energy to find the spring constant of the toy. We haven’t done as much having students decide what measurements to take as I’d like, so students struggled a little at first with what measurements to take. I showed them a strategy from one of my past AP students wo would write out the equation she was going to use to solve for the target variable, then put check marks next to each of the other variables once she had a step in her procedure that would get her a value for that variable. That was exactly what students needed to get a solid plan for the practical.

AP Physics 1: Unbalanced Torque

This week, we worked on unbalanced torque. We used another Pivot Interactives activity (Disclaimer: I work for Pivot Interactives as a content writer. This activity should be published soon!) since I haven’t had a chance to play with the hands-on equipment we purchased for rotation in fall 2019. I’m trying to be pretty conscious of making explicit connections to unbalanced linear forces, both to make sure students aren’t starting from scratch in their understanding and to embed review of earlier topics. Students are seeing those connections pretty clearly, which is great to see.

I also started a countdown to the AP Physics exam on my whiteboard, and noticed students are more focused when working problems. I think the countdown is adding some sense of urgency to what we are working on.

Days 128-132: Energy Conservation & Rotational Kinematics

Physics: Energy Conservation

This week we worked on making the transition to setting up problems for conservation of energy. Before doing problems, we did a card sort where students matched scenarios to energy bar charts, conservation of energy equations using only energy forms, and conservation of energy equations where the formulas were substituted for the energy forms. This seemed to really help students connect the two different versions of the conservation of energy equations and were something I was able to refer back to when students were working on calculations on paper. Whenever students refer back to an activity as we tackle the next challenge, that is a sign to me that the activity was worthwhile.

AP Physics 1: Rotational Kinematics

This week we worked through rotational kinematics. We started with an activity on Pivot Interactives where students analyzed the motion of some dots on a spinning wheel (disclaimer: I write activities for Pivot Interactives. This one should be published soon!). Students very quickly made connections to linear kinematics, which was exactly what I was hoping for. From there, we did a card sort with motion graphs for rotational kinematics where students again saw the connections to linear kinematics really clearly. I’d printed and cut this card sort back in February 2020 with the intention of using it that spring, so it was exciting to finally pull it out of the cabinet! One of the advantages of students making those connections is these activities served as a really natural review, which I try to incorporate into these last topics as the countdown to the AP exam begins.

Days 123-127: Kinetic Energy & Centripetal Force

Physics: Kinetic Energy

The biggest task this week was a lab to determine the equation for kinetic energy. On some recent labs, students have struggled to get good data. I think part of the issue is many don’t buy into the idea that knowledge should come from the labs they do, so they don’t invest the effort or attention into getting good data, which makes it hard to see how it leads to physics concepts or equations and becomes a self-reinforcing cycle I wanted to interrupt with this lab. We talked a little about what I observed and my hypothesis, then I re-did the gravitational potential energy lab as a demo and made a point of discussing the things I was doing to get good measurements and check the quality of my data as I went. When we were getting ready to whiteboard, I also checked in with groups to make sure they had quantities on the correct axis and were seeing that they needed to linearize. The result was data that really nicely showed the quadratic relationship between kinetic energy and velocity and most graphs even had slopes very close to half the mass of the carts students used! A lot of students were really proud of their results, which was great to see and I’m hoping will encourage them to continue those good data collection practices.

AP Physics 1: Centripetal Force

I like to ignore the College Board’s recommendation to do centripetal force as unit 3 because it is such a nice opportunity for built-in review of a lot of ideas about forces. We started by spinning some rubber stoppers on strings to talk qualitatively about how we could change the force in the string before moving over to Pivot Interactives to collect quantitative data (disclaimer: I am a content writer for Pivot Interactives). Next, we used an activity I originally got from Lucas Walker using exoplanet data to find the law of universal gravitation. Students are making the connections I want them to, but I can tell they are starting to feel some fatigue. I typically rely a lot on Pivot Interactives for this topic since we don’t have much equipment, but students got pretty into the brief hands-on activities we did this week, so I think I should make sure to keep working those in to help my students stay engaged these next few weeks.

Days 113-117: Final Exams

This week wrapped up trimester 2. Staff and students alike are very ready for spring break.

Physics

We stuck with our usual structure of using half the final exam period for a lab practical and half the period for an individual written final. One of the interesting things is that while students have been struggling to collect high-quality data during labs, most groups had pretty accurate results on the lab portion of the final. I think a lot of students have been struggling to connect different representations in general, including how their lab data connects to the concepts and mathematical models we are using. If students see the labs as disconnected, why should they invest the effort to get good quality data? I think that’s become self-reinforcing because when few groups have good quality data, it is harder to see the connection between the labs and the models we are developing. The new trimester will be a good time to interrupt this cycle. I think we will try collecting data as a class for a lab so that I can model things like graphing as I go and re-doing data points that don’t match the apparent pattern. On the final, I think grades provided an extrinsic motivation for high-quality data. I don’t want to default to making data quality a part of a students’ grade in my current grading system, but I could provide other extrinsic motivation like stickers for being below a given percent difference from the accepted value.

AP Physics 1

Students took a practice AP exam for their final. I’m really pleased by how well students scored, especially I gave students the full multiple choice even though there are some topics we haven’t covered yet. On the free response, I noticed some students struggled with parsing what the question was actually asking for, which is not unusual. Especially once we wrap up content and focus on review, I think I need to make sure we spend time on reading strategies for making sense of AP problems.

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 105-109: Energy & Pendulums

Physics: Energy

Students did a lab to introduce energy where they pulled carts up ramps at different angles, always raising the cart to the same height above the table, then measured the average force they needed and the distance they had to pull the cart for each angle. Then, they sketch force vs. distance graphs and see they always have the same area. The data was rough enough this year that students could see that a steeper angle required a larger force and a smaller distance, but the areas varied a lot. We’ve had a few labs lately where the data came out pretty rocky. I think part of what’s going on is it’s been tough this year in general for students to see connections between what happens in the lab and the physics concepts we are learning. If the labs are something disconnected from the rest of your learning, why would you invest time and attention into collecting high-quality data? We’re also at the end of a trimester when more students than usual are scrambling to raise their grades after an unusually challenging term and the February doldrums have been hitting everyone harder than usual, so students have less attention and mental energy to go around than usual. Aside from the final, we won’t have any more labs until tri 3, which is a good time for a fresh start. In the meantime, the other physics teacher and I need to do some thinking about how we will continue to draw connections between labs and physics concepts and make sure students have what they need to get good-quality data.

AP Physics 1: Pendulums

This week, we started working on simple harmonic motion. For the first activity, students used a video from Pivot Interactives that shows a pendulum, a cart attached to springs, and a spinning disk all in synchronized simple harmonic motion. Students made position vs. time graphs for each object, which always works well for some discussion not only of how the motion of all three is similar, but to establish some important ideas like the non-constant force and the repeating patterns in the motion of each object. After that, we dove into a deeper focus on pendulums by doing a lab to find the factors that affect the period of a pendulum. This model is going to be split over spring break, which got me thinking about how I currently have the unit structured. Right now, I have one standard for pendulums and one standard for springs. But, especially since I start by emphasizing how similar those two kinds of motion are, I wonder if it would make sense to instead have a standard about using multiple representations like motion graphs and energy bar charts to describe simple harmonic motion that includes both springs and pendulums, then a separate standard on the mathematical relationships and factors that affect the period which also applies to both pendulums and springs. That seems like it would better represent the different kinds of thinking I ask students to do over the course of the unit.