Students worked on developing Kirchoff’s Laws this week. We started with PhET’s circuit construction kit, then got out the power supplies and resistors. Some groups had trouble recognizing the simulation and the physical lab as addressing the same concepts, but explicitly asking groups how their results compared seemed to help students make the connections. There was also some good discussion about why the results in the physical lab didn’t match the simulation exactly. A thermal photo showed some heat at the alligator clips, which lead to some conversation about whether the wires we were using were ideal.
Physics: Energy Transfer Card Sort
This week we worked on starting energy conservation problems. To help the transition from bar charts to problems, I turned some problems Kelly O’Shea and Mark Schober wrote for the New Visions physics curriculum into a card sort. Seeing cards with two versions of the conservation of energy equation seemed to help a lot of students see how to build equations from the bar charts, which made the problems much smoother than in the past.
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 did a lab in Pivot Interactives to find Coulomb’s Law. I debate every year whether I want to take the time for doing a lab, but I’m always glad when I do. In previous courses, students have simply taken it on faith that like charges repel and opposite charges attract, so it’s really powerful for students to make observations that support that rule. My students in AP Chem have also learned Coulomb’s Law is an inverse-square rule and get excited when the realize their physics lab backs up what they learned in chemistry.
Physics: Energy Pie Charts
We did a lot of work this week on what energy is and practice sketching energy pie charts. One of the best activities we did was “Representations Jeopardy”, where each group whiteboarded a set of energy pie charts. Then, they gave their whiteboard to another group who had to come up with a scenario or story to fit the pie charts. In a class where I usually struggle to get students talking to each other, it was great to hear all the noise, laughter, and engagement. During both phases of the activity, students were genuinely having fun coming up with wild stories to fit the pie charts.
Students were also very vocal this week that mistakes whiteboarding is one of the most useful activities we do and is when they feel like the material really clicks. I’ve been thinking about doing less mistakes whiteboarding since I’m really struggling to get kids to speak up during those discussions this year, so those student comments were a good reminder I should be thinking about how to help them speak up more, instead.
We had a four-day student week for a professional development day on Friday.
AP Physics 1: Waves
This week week we worked on developing and using the wave equation, as well as a few other concepts on mechanical waves. We started with a standing wave lab in Pivot Interactives. On a few labs this year, students haven’t taken the time to get good quality data, which has made it tough to make sense of the slopes during the board meeting. As students are getting better at constructing new ideas from lab results, they are starting to really see the value in having good results to discuss and this lab was a place I saw it really pay off. Students worked through linearizing their graphs and figuring out units of their slope with very little intervention from me partly because they knew those steps would help their sense-making and partly because they are getting more skilled and need less support. Every group had beautiful data for the board meeting and, as we worked on problems later in the week, I heard a lot of students referring back to their graphs or their qualitative observations to think through a problem. All around, this was a really fun week to watch and listen to my students.
Physics: Momentum Transfer Practical
Students worked on applying conservation of momentum to problems, including a lab practical. For the practical, students had to determine an unknown mass using photogates and a dynamics track. The groups that were able to sketch momentum bar charts that matched the collision they decided to do were typically able to find their mass pretty quickly, but a lot of students struggled to connect their bar charts to what was happening on their lab table. As we move into energy, I need to think about how I’m going to make sure students are connecting representations like bar charts to things they can observe or interact with in the lab and beyond. I did enjoy seeing the different approaches groups took to the practical. One based their approach on cart explosion lab and added mass to their empty cart until both carts had the same velocity after the explosion.
This week was mostly about working problems for simple harmonic motion. I kept the focus on representations, including free-body diagrams, energy bar charts, and motion graphs, which made it a good review of a lot of mechanics topics. I also was really pleased when a student was checking out the topics we have left to cover on the AP Physics 1 Your Course at a Glance and asked if our unit on mechanical waves will have anything to do with the simple harmonic motion we’ve been working on.
Physics: Momentum Card Sort
This week, we worked on transitioning to calculations with conservation of momentum. We started with a collision lab from the Modeling Instruction curriculum, then did Kelly O’Shea’s momentum representations card sort. I’ve had a lot of students asking for me to do example problems before they work problems on paper, which I try to avoid. The card sort seemed to fill that need for a lot of students, while keeping the focus on their sense-making. I definitely want to work on a similar card sort for energy.
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.