# Days 53-56: Impulse & Vector Addition Diagrams

After a staff development day on Monday, we started trimester 2 this week. This trimester, I’m adding two sections of Physics to my teaching load.

AP Physics 1: Impulse

This week we spent a lot of time working with impulse. Near the end of last trimester, it clicked for me that my students have been very quick to grasp conceptual thinking and can do great on problems like those from TIPERs, but need more practice than I’ve been giving them on calculations. To help with that, we did a lot of whiteboarding calculations this week and did a lot of work making sure everyone grasped the connections between momentum bar charts, force vs. time graphs, and the equations we’re working with. This was the kind of week where I really saw the value of frequently changing groups; since students were with different people almost every day, they were pushed to do a lot of explaining their thinking to each other rather than falling into the shorthand that can happen when you are working with the same people consistently.

This week, we did a lot of work translating between free body diagrams and vector addition diagrams. We did an activity I love from Casey Rutherford where students make arrows out of pipe cleaners over the FBD, then rearrange them to make the VAD. Students had done some practice with this at the end of last trimester, so things went pretty smoothly, but it was helpful for me to start getting a feel for what they have down and what they need more work on before we start adding in calculations.

One thing that felt a little tricky this week has been figuring out how to establish the classroom culture that I want. Usually, around half of our students stay in the same hour for physics when a new trimester starts, so I’ve gotten used to have to do some culture-building at the start of a trimester for the students who are new to the hour, especially if they had the other physics teacher, but I have a foundation to build on thanks to the students who’ve been in that hour since September. What’s been tricky this week is there is still a core of students who have been with each other in this space doing physics together since September, but they were with a different teacher who has some differences in the kind of culture he builds, so I’m asking students to unlearn some things that have been established as part of physics class for the majority. I’m trying to be really explicit about why I’m doing things the way I am and leaning much harder into culture-building strategies than I normally do at this point in the year, but I think we’ll get here.

# 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 75-79: Values and Beliefs & Elastic Potential Energy

This week has felt a little weird. Coming back from break, we’d gotten some messages to be ready to shift to virtual learning and all week the number of students and staff out went up, so everyone felt like we were in limbo. Near the end of my teaching day today, we got word that next week will be remote.

Physics: Values & Beliefs About Physics Learning

We started this week with a version of the values and beliefs lesson from Kelly O’Shea. There wasn’t as much discussion within groups as I was hoping (and it probably didn’t help that I was giving groups more space than usual to try and reduce my COVID exposure), but students had some great insights and really interesting things to say on the individual reflections I had them complete. One thing I felt like was missing in how I implemented this was some conversations about the costs and benefits of different views of physics and physics learning. One of the last things I had students do in their groups was pick some values or beliefs they think we should aspire to, and a lot of groups said we should aspire to do a better job of valuing memorizing facts and equations. I wonder if giving more space to why certain values and beliefs are or are not given a space in a particular classroom would have helped with some conversation about why they see memorizing as important and whether that is compatible with our classroom.

After two days of that, we spent the rest of the week on some problems about pushing cardboard boxes based on problems in Matt Greenwolfe’s More Models in Modeling materials. My goal was to refresh students on velocity vs. time graphs and free-body diagrams before we dive into momentum. There was a lot of great discussion, with lots of animated arguments. I was also really pleased at how often I could have students simply add a diagram, such as a system schema, to identify and fix their mistakes. I still need to work on how to facilitate a good whole class discussion with these problems, but I think part of the issue is I approach these problems with what I call consensus-building discussions, where I have every group whiteboard the same problem, then we try to resolve differences, but I don’t do this type of discussion very often so students don’t have much practice with it.

AP Physics 1: Energy

This week, we focused on going from LOL diagrams to doing calculations with conservation of energy. We started by doing a lab to find the equation for spring potential energy, which gives us all of the major energy types, then did a card sort that included equations based on just the types of energy and equations based on measurable quantities like velocity, mass, and height. The card sort made for a very nice bridge between the two types of mathematical representations.

# Days 35-37: Lab Practicals

The Minnesota teacher union has our convention on this week, so we only had school Monday through Wednesday. I think staff and students alike are feeling pretty run down, so this is good timing for everyone to take a break.

Physics: CAPM Practical

This week, students worked on the “catch the loot” lab practical for constant acceleration. After how smoothly paper and pencil problems went last week, I expected the practical to go very smoothly, but students really struggled. I also found a lot of groups were not interested in testing their calculation with the materials. I think I underestimated how difficult it is for my students to draw connections between what happens in the lab and what happens on paper. I teach all of my physics sections in the morning, so when my colleague who teaches physics in the afternoon saw how challenging the practical was, he added a brief whiteboarding activity to help bridge the paper and pencil problems to the practical, which seemed to really help his classes. Going forward, I need to make sure I plan how I will help students make better connections between what happens in the lab and what happens on paper.

Students also had their quiz over constant acceleration calculations this week and many of my students were really worried after having their confidence shaken by the lab practical. On the quiz day, I took the first half of the class to have students whiteboard a word problem, which they were able to nail with minimal help from me and seemed to really improve the tone of the class before the quiz. I shared my reasoning for doing that problem, and a student made sure to tell me how much she appreciated that I am paying attention to where they are at and trying to adjust to what they need, which was a good reminder that talking about my reasoning for instructional decisions can do a lot to help students feel less frustrated in my classroom.

AP Physics 1: Balanced Forces Lab Practical

Students did a lot of practice with applying math to vector addition diagrams, including a lab practical to find an unknown mass. My students were quick to recognize the math that would be useful, but weren’t always comfortable with how to use the math. I really appreciated the small class size I have in AP since I think that has helped the class feel more cohesive, which has meant students are very comfortable asking each other for help and very willing to patiently work with their peers when asked for help. The small class size has also made it easier for me to step in before students start to experience any serious frustration and has helped me build trust with my students that I will be able to coach them through things if needed. Knowing the positive impact the strong relationships students have with each other and have with me, I need to keep thinking about how I can do a better job of building relationships in my much larger physics classes.

# Days 98-102: Circuits Intro & Energy Bar Charts

AP Physics 1: Circuits Intro

We used PhET’s circuit construction kit to introduce some circuit basics and develop Ohm’s Law. Afterward, we used nichrome wire to test how the length of a wire affects its resistance. The data came out great, with groups that used thinner gauges of wire consistently getting larger slopes than groups who used thicker gauges. I usually skip over resistivity, but, at the AP reading last year, Wayne Mullins shared how he uses resistivity as a conceptual basis for Kirchoff’s Laws and I’m really excited to try that approach with my students this year.

Physics: Energy Bar Charts

This week was all about switching over to energy bar charts. I also noticed students are getting much more vocal during whiteboard sessions. I can’t figure out what’s behind it, but I’m really enjoying it. We’re getting close to the end of the trimester, and a lot of students switch between hours (or even between teachers), so I’m starting to think about how I can help students maintain this progress at the transition.

# Days 80-84: SHM Labs & Momentum Bar Charts

AP Physics 1: SHM Labs

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.

# 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 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 20-23: Newton’s 1st LAw & Constant Acceleration Model Building

This week was a little goofy. Students were off Friday for a staff development day and it was homecoming week, so classes were shortened on Monday and Thursday for festivities.

AP Physics 1: Free-Body Diagrams

This week was all about Newton’s 1st law. We started with the bowling ball lab to come up with a formulation of N1L, then worked on representing forces with free-body diagrams and system schema. Both sections had mistakes whiteboarding sessions that were overall really good. There was a debate about whether a projectile should experience air resistance that had a lot of good thinking. We ended up grabbing a softball out of the storeroom and capturing an image of it rolling in Motion Shot to see if it had a constant velocity. There was a much more intense debate about air resistance than I’ve seen before and I think the group presenting felt like it became a “gotcha” moment. I need to think about how I could have intervened differently in that discussion to shift the tone it took on.

Physics: Constant Acceleration Model Building

Students used video analysis to produce graphs of the motion for an object on a ramp. I was ornery about making students attempt to follow a reference guide I made before I’d help with the technology, which made it a lot easier for me to spend time with students who needed help troubleshooting. The results were better than when I’ve used photogates, but still fairly messy. I think part of the problem is, regardless of the approach, students rush on key pieces and get sloppy data as a result. I need to think about how to slow my students down at key steps. It was also tough to get students to speak up during the board meeting, even with doing a gallery walk and jotting down some observations with their group beforehand. I’ve got more students than usual who underestimate how much they know and are wary of jumping in as a result. I have some work to do on increasing the social safety in my classroom and helping students recognize their contributions.

Students also did Kelly O’Shea’s CAPM card sort. Interestingly, even though this fell on the day of our homecoming pep fest, students were overall very engaged in the activity. I saw a lot of the same students I struggled to get to speak up during the board meeting asking great questions and sharing ideas during the card sort. I think the small group setting was a factor. I need to give some thought to what else made students comfortable speaking up so much in their small groups and how I can bring that to whole class discussions.

# Days 1-4: Dowels & Buggies

School started on Tuesday! This week was all about setting the culture for my classes.

AP Physics 1: Buggy Lab

We dove right in and started the buggy lab on day 1 to start building the constant velocity model. Once again, I used Frank Noschese’s take that “Any lab worth doing is worth doing twice.” On day 1, I just told students to make a graph on a whiteboard that represented their buggy’s motion. There was a lot of variation and other messiness in the whitebaords, which lead the post-lab discussion naturally into how we could prepare whiteboards in a way that set us up for a better discussion. On Day 2 and 3, we repeated the lab, but with some agreements in place to make the whiteboards easier to discuss.

Last year, this approach felt like I was doing some “expose and shame”, but I really liked that it gave an authentic reason to agree on certain details as a class before data collection. This year, I tried to address that by starting the discussion on day 1 by explicitly addressing the fact that every group met the standard set in the directions I gave and talking about the benefits of the different representations we saw. When we switched to talking about changes to the lab, I emphasized that we would be approaching the second round with a focus on being able to communicate and compare results. I also kept the focus on what students needed from me, rather than what students needed to do differently, if we were going to focus on communicating and comparing. This framing of the discussion felt much better to me.

Physics: Dowels

Partly to avoid sharing equipment and partly to limit how much students have to retain from the first lab, we started by asking students to predict the mass of a large dowel by finding a relationship between the mass and volume of smaller dowels. Similar to AP, we did the lab twice. On the first day, I just asked students to predict the mass of the large dowel, and many ended up using measurements from a single smaller dowel. That lead to some nice discussion on how measuring more small dowels would reduce uncertainty. It also lead nicely into graphs as an easy way to look at the ratio between mass and volume of several dowels simultaneously. For the second round of the lab, students used the lab template I put together for the course.