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.
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 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.
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.
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.
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.
This will probably be my last post of the year. Today was the last day for seniors, so my Physics and AP Physics 1 classes wrapped up today. My Chemistry Essentials class is mostly juniors, which means they will continue through the end of next week, but I’ll miss out since I’m going to the AP Physics reading.
This year, I’ve been doing a lot of work to try and build a strong whole-class culture and, compared to previous years, I had a lot more students talk about how they’ll missing being in their specific hour of physics, suggesting there was a strong sense of community. That was a really exciting element of my last day for the year.
AP Physics 1: Final Project Presentations
We finished up final project presentations. There was one group that designed and built a rig to reliably launch a hockey puck to measure the stopping distance along various surfaces in order to determine toe coefficient of friction. For the final, students were given a spring with a known spring constant and tasked with finding the mass of a mystery object.
Physics: Lab Final
Students did a lab practical for the second half of their final exam. There was lots of great conversation as students worked through the problem and it was a lot of fun for me to see students using so many of the skills we’ve been working on this year.
Chemistry Essentials: Nuke Whiteboarding
We did a quick refresher on nuclear decay using the whiteboards before taking the quiz on nuclear chemistry.