We spent most of the week on the pendulum lab exploring the variables that affect the period of a pendulum. This will be our last model-building lab for the year, so it was good to see students figuring out plans for data collection and getting high-quality data with minimal intervention from me. Connecting the data to a mathematical model was still tricky for students, but they worked through the challenging parts to figure out what was going on. They really hated the unit on the slope of their period vs. square root of length graph (I don’t blame them!), but I was able to use that as motivation to try and get a nicer unit by rearranging things so that we had the length divided by a number in m/s2. From there, students were quick to suggest that the slope has something to do with gravity. From there, I showed that the value happened to work out if we put a 2π out front. This approach could use some refining, and I’d especially like to put more of the thinking on students, but students did seem clearer on the significance of the slopes of their lines than in the past.
AP Physics 1: Review
With the AP exam on Thursday, the first three days of this week we focused on review. My students this year really liked Plickers for multiple choice and had some great discussions, when whole class discussions have generally be tough this year. I wonder if I should have pulled out Plickers earlier in the year as a way to get them talking and to build up to some other types of class discussions.
I had a brainstorm for a review activity, that unfortunately came the day of the AP exam, so too late to try. I do a lot of having students start by just looking at the diagram and scenario description, then deciding what models seem useful and sketching some diagrams. It crossed my mind this could lend itself to a card sort, so I put one together with the released free response to date. I haven’t tried it with students, but I think I would start by having students match each prompt to at least one of our models, then give each group a problem to sketch some diagrams and brainstorm what they could figure out.
This week was a little hairy since students were in and out for AP exams. We continued working on using velocity vs. time graphs to quantitatively describe the motion of projectiles. We wrapped up the week with a practical to predict how far from the edge of the table a marble will land. I spent more time than usual working on breaking up the three phases of motion (constant acceleration while the marble is on the ramp, constant velocity while it rolls across the table, and projectile motion once it leaves the table), but it was still pretty challenging for students to connect when to use the measurements they made in their calculations. Based on the conversations I had with students, I think this fits in with a larger pattern I’ve seen this year with students struggling to connect labs to mathematical and graphical representations. As we move into the last few weeks of the school year, I want to make sure I keep thinking about how to support students in seeing the mathematical and graphical representations as meaningful descriptions of something physical.
AP Physics 1: AP Review
We continued reviewing for the AP exam. I didn’t do anything particularly interesting. We started each day doing a few multiple choice questions on Plickers, then moved into working some released free response. For the free response, I let students pick problems to work on based on the topics they want to work on reviewing. With both the multiple choice and the free response, I made sure we spent some time discussing what the problems illustrate about the type of things that tend to show up on the exam, things that tend to show up on the scoring guide, and strategies for approaching the question. A lot of my students have resisted using the formula sheet this year, and it’s been good to see students getting more comfortable referring to it this week and even using formulas to figure out the significance of the slope and area of graphs they are rusty on.
It’s been tough for students to make connections between labs, diagrams, and mathematical representations this year, so I was nervous about the shift this week from sketching diagrams for projectile motion to doing problems. I had a brainstorm on my way to work for scaffolding that transition that worked out really well. First, we did a lab practical where each group got a strip of clear acrylic and a random time. They were tasked with calculating how far apart they should place pieces of tape so they could get a photogate to read their time. That meant students only had to think about the vertical motion, which seemed to help with connecting measurements, diagrams, and mathematical representations.
The next day, I wanted them to think about motion in both directions, but keep the distinction between those two directions very concrete. We tried a lab practical I’ve seen where each group got a random distance for a constant speed buggy to travel, then had to calculate where to drop a marble from so it would land in the buggy. The two separate objects seemed to help students wrap their heads around what we mean by the vertical motion and what we mean by the horizontal motion and why the time must be the same for both.
At this point, we talked a little about how thinking about the motion of the buggy and the motion of the falling marble simultaneously was similar to thinking about the motion of a projectile. Students seemed to make that connection really nicely. One benefit I hadn’t thought about in advance is they also seemed more confident starting the problems, having already had multiple, tangible successes with this kind of thinking. This seems like it could be an argument for putting lab practicals or similar experiences early in a unit, rather than only toward the end where we tend to use them.
AP Physics 1: AP Review
We wrapped up angular momentum and started reviewing for the AP exam. We spent some time on model summaries, where students revisited the diagrams and equations central to each major model we’ve used this year. The next day, I handed out the 2021 free response and we took some time to just read the problems and talk about things the students noticed. Next, I gave students the scoring guide and we made some observations. Finally, I handed out the student samples that are publicly available to make more observations. This lead to some good discussion about what the readers are looking for as well as some good conversation about strategy, like how to make use of diagrams or the importance of taking the time to break apart the text.
We had Friday off this week. I think staff and students alike were very happy to have a long weekend.
Physics: Popper Hoppers
This week we wrapped up energy. After finishing the bouncy ball evidence-based reasoning from last week, we got out the popper hoppers to use energy to find the spring constant of the toy. We haven’t done as much having students decide what measurements to take as I’d like, so students struggled a little at first with what measurements to take. I showed them a strategy from one of my past AP students wo would write out the equation she was going to use to solve for the target variable, then put check marks next to each of the other variables once she had a step in her procedure that would get her a value for that variable. That was exactly what students needed to get a solid plan for the practical.
AP Physics 1: Unbalanced Torque
This week, we worked on unbalanced torque. We used another Pivot Interactives activity (Disclaimer: I work for Pivot Interactives as a content writer. This activity should be published soon!) since I haven’t had a chance to play with the hands-on equipment we purchased for rotation in fall 2019. I’m trying to be pretty conscious of making explicit connections to unbalanced linear forces, both to make sure students aren’t starting from scratch in their understanding and to embed review of earlier topics. Students are seeing those connections pretty clearly, which is great to see.
I also started a countdown to the AP Physics exam on my whiteboard, and noticed students are more focused when working problems. I think the countdown is adding some sense of urgency to what we are working on.
This week we worked on making the transition to setting up problems for conservation of energy. Before doing problems, we did a card sort where students matched scenarios to energy bar charts, conservation of energy equations using only energy forms, and conservation of energy equations where the formulas were substituted for the energy forms. This seemed to really help students connect the two different versions of the conservation of energy equations and were something I was able to refer back to when students were working on calculations on paper. Whenever students refer back to an activity as we tackle the next challenge, that is a sign to me that the activity was worthwhile.
AP Physics 1: Rotational Kinematics
This week we worked through rotational kinematics. We started with an activity on Pivot Interactives where students analyzed the motion of some dots on a spinning wheel (disclaimer: I write activities for Pivot Interactives. This one should be published soon!). Students very quickly made connections to linear kinematics, which was exactly what I was hoping for. From there, we did a card sort with motion graphs for rotational kinematics where students again saw the connections to linear kinematics really clearly. I’d printed and cut this card sort back in February 2020 with the intention of using it that spring, so it was exciting to finally pull it out of the cabinet! One of the advantages of students making those connections is these activities served as a really natural review, which I try to incorporate into these last topics as the countdown to the AP exam begins.
This week, we came back from spring break and started trimester 3.
Physics: Energy Bar Charts
This week we focused on drawing energy bar charts. Students have struggled to connect representations, so I tried starting by having students draw the more familiar energy pie charts. Then, we got out the Mathlink cubes to use as a manipulative representing the types of energy (an idea I think I first saw in Scott Hertting’s article in The Physics Teacher). Once students had rearranged the cubes to represent at least two different snapshots, I had them sketch how they arranged the cubes on a bar chart. One thing I was really excited about is as the week progressed, I had some students ask if they could keep using the cubes, which tells me they were a useful tool. I also saw a lot of students sketching energy pie charts to help figure out what the bar charts should look like, which tells me they are connecting the two representations when seeing relationships between representations has been really challenging this year.
AP Physics: Oscillating Springs
Students did a lab to find the equation for the period of a spring, then we dove into some problems. Students did really well with the problems focused on representations and showed a lot of growth from earlier this year on the problems from the College Board’s AP Physics 1 workbook. The workbook problems included a lot of predictions about how various factors would affect the period of a spring, so we used a spring to connect a motion encoder cart to a force sensor on a track so we could change the angle the spring was at, as well as factors students had already tested like mass and amplitude. I also made sure to use this as an opportunity to review some basics on motion graphs since exam day is starting to loom.
This week wrapped up trimester 2. Staff and students alike are very ready for spring break.
We stuck with our usual structure of using half the final exam period for a lab practical and half the period for an individual written final. One of the interesting things is that while students have been struggling to collect high-quality data during labs, most groups had pretty accurate results on the lab portion of the final. I think a lot of students have been struggling to connect different representations in general, including how their lab data connects to the concepts and mathematical models we are using. If students see the labs as disconnected, why should they invest the effort to get good quality data? I think that’s become self-reinforcing because when few groups have good quality data, it is harder to see the connection between the labs and the models we are developing. The new trimester will be a good time to interrupt this cycle. I think we will try collecting data as a class for a lab so that I can model things like graphing as I go and re-doing data points that don’t match the apparent pattern. On the final, I think grades provided an extrinsic motivation for high-quality data. I don’t want to default to making data quality a part of a students’ grade in my current grading system, but I could provide other extrinsic motivation like stickers for being below a given percent difference from the accepted value.
AP Physics 1
Students took a practice AP exam for their final. I’m really pleased by how well students scored, especially I gave students the full multiple choice even though there are some topics we haven’t covered yet. On the free response, I noticed some students struggled with parsing what the question was actually asking for, which is not unusual. Especially once we wrap up content and focus on review, I think I need to make sure we spend time on reading strategies for making sense of AP problems.
We are almost at the end of the trimester! Both classes wrapped up a topic, then started reviewing for the final.
Physics: Constant Acceleration & Balanced Forces
Students worked on a packet of problems. One nice thing is many students were working more independently than usual, so it was easier for me to give more intensive support to students who’ve been struggling. It was really great to see how many students had moments where something we’ve been working on finally clicked.
AP Physics 1: Model Summaries
We started the final review with model summaries, where each group takes a model from so far this year and prepares a whiteboard with the major representations including graphs, diagrams, and equations. My students didn’t have as strong a positive response this year as in the past, and I think that is probably related to some conversations I had this week where students weren’t aware that this class is organized by models. This tells me I need to get more intentional about using that language if I want students to think in terms of what models we have.
With the AP Physics 1 exam on Thursday, I decided not to assign anything so students could focus on reviewing, especially since many of my students were taking other AP exams earlier in the week. The couple of students who checked in after the exam said they felt really good about how it went, which was great to hear.
Physics: Pendulum Assessment
Students worked on applying the equation for the period of a pendulum to some problems and a short summative assessment. Students felt really good about this module; it involved a lot less conceptual knowledge than previous modules and didn’t require students to connect to many old ideas, which I think made it easier. I recently heard from a few students that between being out of school for all of March and not having access to old packets they’d left in their locker, they were having a very difficult time with the fact that the first two modules revisited old concepts, like motion graphs. I think it’s worth putting some thought into how we can do a better job of giving kids resources for going back to old ideas during distance learning.
Chemistry Essentials: Balancing
Students worked on some problems balancing chemical equations. The couple of kids I’ve talked to are now buying in to particle diagrams since they make balancing so much more concrete. Prior to balancing, particle diagrams were the first truly new content we’d done via distance learning, and I had some students who really pushed back on trying to get them down. It’s great to see some of those same students now recognizing the value of that representation.
Students used Pivot Interactives to find a relationship between torque and angular acceleration. The activity has several different bicycle wheels, which lead to some good discussion on the forum as students first compared their results to someone with the same wheel, then compared results to someone with a different wheel.
In both the questions I got about the activity and in the grading I was doing this week, I saw a lot of students struggling with the distinction between different terms related to gravity. That’s been an on-going challenge this year that I think is related to having some students who use a lot of verbal shortcuts. We’ve made a lot of progress on that front this year, and a lot of students were joining me in pushing back whenever someone used imprecise language. I think with out that consistent feedback on language, some students are falling back to old habits. I’m giving feedback on language in students’ written work and sent out a vocab review to all of my students, but am thinking about other options.
Students used Pivot Interactives to collect data we’ll use to get the equation for the period of a pendulum. This week, we had students collect data, then post their graphs and answers to a few questions to a forum. Next week, they’ll start by linearizing the period vs. length graph. Based on the forum, I’m glad we split the lab up. In the questions, students recognized angle and mass don’t affect the period and correctly explained why the period vs. length graph should have a zero intercept. However, most students described their period vs. length graphs as linear in spite of the large intercepts. Using the discussion and splitting up the lab gave me a chance to catch the issue and record a short video before students started their linearization. It’s been hard to be responsive when I have almost no contact with my students right now, so it felt good to have this opportunity to shift my instruction based on students’ current thinking.
Chemistry Essentials: Pressing Pause
The representing reactions summative was due on Tuesday, and only two of my students had turned in work for the module. Rather than sticking to my plan to start balancing, I pushed everything back so that students have an extra week to catch up before their next assignment is due. I also spread out the remaining work in an effort to reduce the workload. We’re shooting for each class to have around 90 min of work per week, so I’ve been assigning what would take around 30 to 45 min in the classroom each week, but the students I’ve heard from are spending around 3 hours a week on chem. I’ve only gotten work or heard from a few kids since Tuesday, but even if just a few more kids get a credit required for graduation as a result of this week’s adjustments, I’m happy with my decision.