Days 75-79: Projectile Problems, Impulse, & Risk Taking

AP Physics 1: Projectile Motion & Free Fall

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.

Days 73-74: Projectile Video Analysis & Cart Catching

We kicked off 2020 with a two-day week. Even with the short week, my students fell pretty easily back into classroom routines.

AP Physics 1: Projectile Video Analysis

I like wrapping up linear mechanics with projectiles since its an opportunity to apply pieces of just about everything we’ve learned so far this year. We spent a day on a problem from Michael Lerner representing an orange in free-fall a bunch of different ways. Then, we did some video analysis of tennis balls. In the past, we’ve had to go to a computer lab to do video analysis, so I provided students with a video. This year, since laptop carts are a more practical option, I had each group record their own video. I’m hoping that comparing graphs from different videos will lead to a richer discussion when we have the board meeting next week.

Physics: Cart Catching

To introduce momentum, we did a lab from Scott Lotze, the other physics teacher at Tartan, and had students catch a cart at the bottom of the ramp, then find as many ways as possible to make the cart harder to catch. This lead to an operational definition of momentum and nicely illustrated that both mass and velocity of the cart matter. A few groups tried the plunger carts and noticed they are usually easier to catch, which lead nicely into impulse on Friday.

A hand catching a cart at the bottom of a ramp

Days 29-31: Vector Addition Diagrams & CAPM Practical

This was a three-day week since public schools closed on Thursday and Friday for the state teachers union conference.

AP Physics 1: Vector Addition Diagrams

Students started the week by doing Kelly O’Shea’s forces representations card sort. I used the card sort to introduce vector addition diagrams, and students easily recognized key aspects of the VAD. The rest of the week, we worked on applying VADs to solve problems. They are successfully applying the VADs, but aren’t feeling confident in their skills just yet.

A completed forces representations card sort categorized into balanced and unbalanced forces.

Physics: CAPM Practical

After wrapping up some problems using the constant acceleration model, students started working on a practical to figure out where to start a marble on a ramp so that it lands in a passing buggy. We ran out of time for students to test their calculations. While students made good progress, many are uncertain of their skills; I’m hoping that completing the practical on Monday will help them build confidence.

Days 24-28: Force Formulas & CAPM Diagrams

AP Physics 1: Balanced Forces

This week was all about figuring out the formulas for gravitational force, spring force, and friction force, then practicing combining them with free-body diagrams. After doing some fairly standard labs to develop the formulas, students did a version Kelly O’Shea’s problem solving stations. I’d like to add a station using the force of friction, but need to make sure there’s a good way for students to check their answer.

This year, I’ve been working on keeping my pace on track, and most students are keeping up. I always have some students who start out goofing off during the daily work because its not graded, but the majority of them are figuring out they need to stay engaged, which is great because students are deciding for themselves that the daily work is valuable and my retake policy means they aren’t stuck with a grade based on choices they made early in the term! The problem is I’ve also got a few students who I see starting a cycle where they are missing pieces because of goofing off, then struggle with what comes next, and disengage more out of frustration. Before students become stuck in that cycle, I need to give some thought to how to help those students feel a greater sense of control over their learning. I think on Monday I might spend some time talking as a whole class about strategies for when students are feeling stuck or frustrated. I’m also trying to be conscious of how I approach those students, trying to keep my focus on communicating I’m available to help rather than chiding them for being off-task.

Physics: Constant Acceleration Representations

Students practiced using constant acceleration representations. A lot of them are having trouble connecting what we’re doing now to constant velocity representations, which happened last year, as well. I need to put some thought into how we structure this unit to help students see how we are extending their skills, rather than starting something completely new.

In whole-class discussions, students are still pretty quiet, though I’m seeing signs of progress. I’m hearing a lot from students how much they like mistakes whiteboarding, even if just a few students are responsible for most of the questions during those activities. There was a great moment where a group presenting said they didn’t want any questions from a peer who’d been very vocal during the other presentations, and he responded “That’s a great idea!” When no one raised their hands, a member of the group started calling on some of the other people she knew had a good grasp of the problems, but rarely speak up. It was a pretty awesome moment.

Days 15-19: Interaction Stations & Constant Velocity Problems

AP Physics 1: AP Workbook

To wrap up constant acceleration calculations, we worked on some problems out of the College Board’s workbook. There was a lot of great discussion as students worked through the relatively complex problems. Students have been nervous about the early registration date for the exam this year, and working the problems seemed to help alleviate some of their fears.

Students also worked through an activity based on Brian Frank’s interaction stations to start building their model of a force. I had a sub that day, so afterward had students use a reading to define the major types of forces we’ll be using in class and connect them to the stations. We’ll be discussing the stations early next week and I’m thinking about how I want to approach the discussion. This week, I happened to read a chapter from Bryan Brown’s Science in the City where he talks about how teachers often miss how accurate students’ preconceptions are because students aren’t ready to express those ideas in scientific terms. I’m wondering how I might change the way I usually approach this discussion (and many others) to do a better job of recognizing and building on what students knowledge, regardless of the language they use to express it.

Physics: Constant Velocity Problems

Students worked problems, including the dueling buggies practical, using the constant velocity of a particle model. On their weekly reflection, a lot of students wrote about navigating different ideas within their groups about how to complete the lab practical. I was really excited to see that multiple approaches were suggested in most groups and that students were thoughtful about how to balance making everyone heard with moving forward as a group.

We also did some mistakes whiteboarding. In both my courses, I’ve been pleasantly surprised by how quickly students are buying in to this activity. My Physics students have been pretty quiet during the whole-class discussions, but they are consistently referencing it in reflections as something they find helpful for learning and where they feel proud of their work in class.

Days 10-14: Constant Acceleration Representations & Constant Velocity Calculations

AP Physics 1: Constant Acceleration Representations

We spent this week working on getting representations for constant acceleration down. I made quite a bit of use of Brian Frank’s magnetic vector manipulatives during class discussions of motion maps. I think it would be worthwhile to make a set for each lab group; I don’t have magnetic surfaces at my lab stations, but I think the laminated arrows would still be useful to students while they’re working.

I’ve been doing more work on collaboration so far this year, and I’m seeing it pay off with students seeking out input from a greater variety of people when they’re stuck and with ideas jumping between groups much more than in the past. I especially love when students start working problems with one group, then whiteboard with different people and begin by comparing approaches.

motion map.jpg

Physics: Constant Velocity Calculations

Students worked on applying the constant velocity of a particle model to calculations, including predicting where two buggies will collide. One challenge, which has come up the past few years, is a lot of students are having trouble connecting the calculations to the representations we’ve been using. I think there’s a couple of things going on. In a lot of classes, once students have taken an assessment, they no longer need to use those skills, so I think some students feel like they are done with constant velocity representations after last week’s quiz. I think the other hurdle is some students, especially those less confident in math, are looking for things they can memorize to bypass the sense-making involved in sketching the diagrams. I haven’t figured out good strategies to help students work through these hurdles aside from coaching individuals and small groups on doing the sense-making and sketching the diagrams when they are stuck. I also need to keep reminding myself that as the year goes on, more will get on board with continuing to use skills we’ve assessed and working through the sense-making steps.

Days 5-9: Board Meetings & Problems

This week’s big theme was using precise, specific language in physics.

Physics: Buggy Lab & Problems

Students did the buggy lab, then worked on some problems with constant velocity representations. We went over the problems using Kelly O’Shea’s mistakes whiteboarding. Both during the buggy board meeting and during the mistakes whiteboarding, students used a lot of phrasing like “the slope is increasing” to indicate a positive slope or even just saying “the buggy was decreasing”, rather than specifying what about the buggy is decreasing, which made for some good opportunities to pick apart that wording and try to find ways to make it clearer what they meant. A few students seemed like they were frustrated by these conversations, especially during mistakes whiteboarding when a group didn’t consider that one of their mistakes, which tells me I need to keep working on emphasizing growth.

buggies

AP Physics 1: Problems & Acceleration Model-Building

AP also had their first round of mistakes whiteboarding this week. While we had some similar conversations about language, I noticed fewer students who seemed frustrated by those conversations. I don’t think I approached getting nitpicky about wording differently than I did in Physics, so I’m not sure if the AP students were doing more hiding their frustration or if they are bringing something to the class that leaves them less bothered by me getting picky about language.

After the problems, we started a model-building lab for constant acceleration where we used photogates to produce a position vs. time graph for a cart on a ramp. This lab is fairly teacher-directed since its the first time students are using any LabQuest probes, and it takes a while to get through. I’ve thought about switching to motion detectors or video analysis, but with the limited computer access I usually have, I like that photogates produce data that students can linearize. My building added a lot more laptop carts this year, so I might try one of the other options when Physics gets to acceleration.