This week was mostly about working problems using the constant acceleration model, which I have students do almost entirely from velocity vs. time graphs. We started with some problems I got from Kelly O’Shea where students are given some velocity vs. time graphs they annotate and write area equations for. Next, we shifted to word problems. I was blown away by how easy these problems were for students. Doing calculations with the constant velocity model had been very challenging for a lot of students, but something really clicked this week. Students were even including units on all of their work with almost no prompting and showing their work really clearly. I’m not sure what it was, but it was nice to have a week where students were nailing what I gave them!
AP Physics: Force Equations
We did labs to find the equations for the force of gravity and for spring force. Most years, my students are most comfortable with mathematical representations and it’s a challenge to get them comfortable with other representations, but this year my students are defaulting to other representations in some really cool ways. At this point in the year, when I have groups make a graph on a whiteboard, they usually default to including an equation for the line of best fit whether or not I ask for it. Instead, my students this year have been writing “for every” statements about their slope unprompted. For example, on the force of gravity lab, every group wrote some variation of “The force goes up 10 N for every 1 kg” on their own. That tells me that my students find the “for every” statements useful and intuitive, which is a great place to be developing physics knowledge from.
This week we did a lot of practicing with constant acceleration diagrams. The highlight was doing mistakes whiteboarding. Based on a recent conversation with Kelly O’Shea, I was much more explicit that the role of the group presenting is merely to facilitate the discussion while the role of the rest of us is to help them get to the right answer. In two of my classes, this seemed to be really freeing for a lot of groups as they presented, and lots of students were quick to ask their peers to justify changes to the whiteboard when they were presenting. There was also some fantastic back and forth where the students who weren’t presenting disagreed about what to change on a whiteboard and had exactly the kind of discussion I’m after with mistakes whiteboarding. In my third section, the discussion was still pretty rough, so I need to give more thought to how I can support them in having deeper student-to-student discussions.
AP Physics 1: Free-Body Diagrams
This week we focused on drawing system schema and free-body diagrams. I was reminded how much I love framing forces in terms of interactions and the discussion that comes out of even the very basic free-body diagram problem set in the Modeling Instruction materials. I love that on a problem about a skater sliding across frictionless ice at a constant velocity, I get to hear students internalize Newton’s 1st Law as they wrestle with what interaction could be giving the skater a forward force. This year, my students also got into Newton’s 3rd Law during the discussion as one student pointed out the ice is pushed downward by the skater’s foot, so the class wrestled with how that impacts the normal force before agreeing that same interaction pushes the skater up and the ice down. We also did Kelly O’Shea’s force diagrams card sort, which I use as students’ first introduction to vector addition diagrams. I was really pleased by how easily they connected the vector addition diagrams to the free-body diagrams and by how they started contrasting balanced and unbalanced force scenarios with minimal input from me.
This year has felt unusually draining so far, but my students are doing some great work in my class and reminding me why this job is worth it.
For the second week in a row, students did a lot of problems on paper and whiteboards. This week, the focus was on using constant velocity representations for calculations. I like the way we gradually add complexity to the model and students definetly need time to practice and discuss, but this has felt like a long stretch where students are doing mostly one kind of activity. I think next year I want to look at our storyline for the unit to see if we can break up the problems a bit with the dueling buggies lab practical, video analysis, and other activities that have a different feel. We also added more problems to our packet a few years ago, so students first work through what we consider the core problems, which includes problems where students are working out how to apply what they found in the lab to the written problems. We found students often didn’t have a lot of confidence after just these problems, so we added a second problem set to the constant velocity packets that are mostly about practicing what students have already figured out. I’m wondering if there are ways we could approach the early problems differently to help students build more confidence and how we could reimagine the second set of problems to focus more on lab practical types of activity.
AP Physics 1
This week was all about constant acceleration representations. We purchased some motion encoder systems last spring, so I used them to have students do a lot more exploring the graphs for ramps than I normally do. My students are getting direction on position vs. time and velocity vs. time graphs much more easily than my students usually do, and I think the tracks are helping a lot. It is still challenging for some students to visualize what is happening to the slope of a position vs. time graph to predict what the velocity vs. time graph will look like, but their struggles are pretty consistent with what I see at this point in the year, so I trust that they will get it down.
I also have a single, very small section and, while I’m sad that more students aren’t taking AP Physics 1, I am really enjoying how cohesive this class is. During mistakes whiteboarding, the students presenting have been admitting unintentional mistakes and the students not presenting have been asking questions about things they don’t understand but don’t think are mistakes, both of which are signs of the kind of class culture I strive for.
This week, both of my classes spent a lot of time working problems to practice translating between different representations of constant velocity. In Physics, velocity vs. time graphs seemed to either click immediately for students, or to be a big struggle. Usually, I have a lot more students with an experience somewhere in between. Regardless, by the end of the week even the students who found velocity vs. time graphs really challenging were getting the hang of them. In my AP Physics 1 class, most students seemed to be in a place where the velocity vs. time graphs were clicking pretty quickly.
AP Physics 1 also was able to do the dueling buggies lab practical. We had some great conversation about the sources of uncertainty in their predictions. Each group took a different approach, but got the same predictions for where the collision would happen, which is always fantastic. I’m also starting to see more of my students’ personalities in this class, which is making this class a lot of fun. AP is a lot smaller than my Physics classes, so I’m not surprised that is starting to feel like a cohesive class sooner than Physics.
This week, I also had a lot more conversations than usual with students who said they “aren’t a science person” or “aren’t good at science”. I suspect some of it is rooted in all the challenges of what science classes looked like last year, but that doesn’t make it any less important for me to address. I’ve been slow to start discussions of what skills groups needed to complete a task, but I need to make sure I’m making time for those. I also found myself telling students if their answers were right a lot more than usual in order to help them get some immediate confidence to keep them moving forward on problems, but the downside is it really limits the discussion students have once one of them knows they have the right answer. I need to figure out how I’m going to balance the need to keep the door open for student discussion with how I’m going to help students feel more confident in my classroom.
Next week are trimester 2 final exams, so after wrapping up our last topic of the term, both my courses started reviewing for the final exam.
AP Physics 1: Model Summaries & AP Classroom
I’m generally skeptical of typical final review activities, but I really like starting with model summaries. I gave each group one of the major models from so far this year and asked them to prepare a whiteboard with the key diagrams, equations, and other representations for their model. A lot of groups found it helpful to start by coming up with a scenario where the model would be useful. Students really responded to the idea that a model is a toolkit, and the model summary is a reminder of the tools in that toolkit.
After the model summaries, I had students go on AP Classroom, where I’d unlocked multiple choice problems from each of the topics we’ve done so far and asked students to pick a topic to complete. Students liked choosing what they wanted to review, but really wanted a chance to whiteboard and discuss the problems. We ran out of time for any whiteboarding, but I’m glad that my students see the value in discussion.
Physics: Final Review Packet
Monday through Thursday we worked on wrapping up energy, then I handed out a fairly standard final review packet. While working through the packet is helping students to feel more confident goin g in to the final, it reminds me that we have a lot of room for improvement in spiraling content and helping students draw connections between models in this course. That said, students had a much easier time with some of the old problems than in past years, which suggests we’re moving in the right direction.
We worked on labs to determine what affects the period of objects in simple harmonic motion. I had half the class experiment with pendulums, while half the class used springs. During the board meeting, we did a lot of jumping back and forth between the two experiments; this lead to some good discussion about energy when we saw that mass mattered for the springs, but not for pendulums. I had each spring group use a spring with a different spring constant, which also lead to some good discussion about why the pendulum groups all got the same slope on their linearized graphs, while each spring group got a different slope.
Physics: Momentum Bar Charts
This week, we developed conservation with cart explosions, then worked on using momentum bar charts to represent conservation of momentum problems. After last week, I spent some time talking about the purpose of giving students time to work all (or most) of the problems on paper and warned them I would be unhelpful when they were preparing their whiteboards, then held to it. When we got to mistakes whiteboarding, I required groups to make at least one of their mistakes in the bar charts. While students were working on paper and preparing their whiteboards, I saw a lot more small-group discussion than usual, both within groups and across groups, which was fantastic. During the whole-class discussion, I also got some students speaking up who are usually pretty quiet and one of my classes even got some really good student-to-student exchanges, which have been very rare this year. On Friday’s quiz, students consistently felt really good about their performance. I’m hoping that the positive experience students had whiteboarding these problems coupled with good performance on the quiz will move the class culture in the right direction.
This week, we worked on problems and calculations for projectile motion and free-fall. A lot of students were rusty on velocity vs. time graphs (like we haven’t used them much in a while or something!), so it was helpful to revisit. I also continue to really like projectile motion as a wrap-up to linear mechanics since we had a chance to revisit pieces of each major topic so far. I was out sick for a day, which made it tough to fit in the practical I usually do while staying on track for pacing. I think the practical could be good for a review in April, especially since I’ve got some ideas for extensions to connect the lab to more concepts.
Physics: Impulse Problems& Risk Taking
We spent most of this week working problems using momentum and impulse and discussing them with mistakes whiteboarding. This week, I was particularly aware of two common behaviors during problems and whiteboarding that suggests students are still wary of taking risks in my classroom. First, when working the problems on paper, I had a lot of students who got off-task if I wasn’t at their table and were really resistant to sharing their thinking if I was. Second, most of the mistakes students picked for mistakes whiteboarding were in parts of the problems that relied on familiar representations, like vector addition diagrams and velocity vs. time graphs, rather than in the new material.
Recently, I had a conversation with an administrator about classroom environments that encourage academic risks and we agreed that before students can take a risk, they need (1) to feel safe and to know the stake are low and (2) a clear sense of how they will benefit or what they will gain, ideally regardless of the outcome. I’m pretty sure I need to put in work on both of those criteria. Some students who I know really appreciate the discussion that comes from mistakes on new material stuck to mistakes on the familiar content, which tells me they aren’t feeling as safe as I ‘d like. Several of the students who were off-task doing problems on paper find the whiteboard discussions extremely valuable, so I think they just didn’t see a benefit to taking the risk or effort of working through their confusion when we were still on paper. All of this tells me I need to keep working to make sure both requirements for academic risk taking are present in my classroom.
This week, students worked on applying conservation of energy. We wrapped it up with a lab practical to find the spring constant of a popper toy. To help with what makes a good procedure, I had groups start by writing out the steps they were going to follow on a whiteboard. Then, they traded whiteboards with another group and had to follow the procedure they were given to actually collect data. One group came up with a nice strategy of writing out the equation they’d use in their calculations, then checking off each variable as they added a step to measure it.
Physics: Pushing Boxes
Students spent a lot of time this week on problems applying Newton’s 3rd Law and synthesizing Newton’s Laws, including some great problems originally from Matt Greenwolfe where students draw free-body diagrams and velocity vs. time graphs for boxes pushed across various floors. While there was some great discussion, I think these problems would have been more valuable much earlier in the forces model. In general, I think Newton’s 3rd Law feels like an afterthought in how we approach forces. With some shifts in what we’re doing early in this model, we could better integrate key elements of this model and reduce the need for doing some kind of synthesis at this point in the unit.
Students worked on sketching bar charts and LOL diagrams to show energy transfers. I was really pleased with how comfortable students were switching between different systems. I started out the week by having students use a spring scale to pull a cart up different ramps, always raising their cart to the same height above the table. We then sketched force vs. displacement graphs to introduce the idea of work and gravitational potential energy. Getting both simultaneously meant the concepts blurred together for students at first, but that issue got resolved as we did mistakes whiteboarding with energy bar charts and LOL diagrams.
Physics: Newton’s 3rd Law
One of our major tasks this week was developing Newton’s 3rd Law. Students started by predicting how the forces on two colliding carts would compare, then we tested out the collisions. As we tested the collisions, I cued students to notice the relative accelerations of the carts, which I think helped students see the useful thinking in their original predictions. Before we officially stated Newton’s 3rd Law, I borrowed an idea from Mark Schober and had students play with film canisters with magnets inside to test and refine their rule before the whole-class discussion.
Students used a modified half-atwoods to find a relationship between force and acceleration. The quality of the results varied a lot. I’ve been talking to the AP Chemistry teacher, and we think part of what’s going on is students aren’t often asked to use their data in meaningful ways before they get to physics, so it doesn’t make sense to take the time and attention to collect data carefully. I need to put some thought into how to help students place value on good data collection and build the skills required to collect good data.
After developing Newton’s 2nd Law, we spent some time combining the new equation with vector addition diagrams. Students are starting to buy in to the diagrams as useful thinking tools, which is always a lot of fun to see.
Physics: Free-Body Diagrams
Students have been working on Newton’s 1st Law and drawing free-body diagrams. We have some problems that often lead to great discussion with mistakes whiteboarding, but I’ve been struggling to get students in one of my hours to speak up during whole-class discussions. To help with that, I tried doing a short gallery walk prior to any of the whiteboard presentations this week. Once the whiteboards were ready, I had students visit each board with their group and make notes on their worksheet about potential mistakes they saw or questions they had. During the whole-class discussion, there was a lot less silence and we heard from some students who don’t often speak up, which was exactly what I was hoping for. I think it also helped that I shared those goals with students before we started. When a student joked those goals aren’t going to happen, I assured her I’m very stubborn and am convinced the class can get there.