Projectile Motion

Days 82-86: Projectile Calculations & Momentum Conservation

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AP Physics: Projectile Calculations

This week we worked on wrapping up projectile motion by focusing on calculations. Students were a little rusty on using velocity vs. time graphs to set up equations since we haven’t practiced it in a while, but I was very pleased with how quickly they got back into the groove with those skills. We ended the week with the classic projectile practical where students predict how far from the table a marble will land and it was great to not only see students nail it, but feel good about nailing it. Once students succeeded, I gave them a lighter marble and asked them to predict where it would land relative to their original, heavy marble, which lead to some great conversation.

Physics: Momentum Conservation

This week we started transitioning to quantitative momentum conservation, including a lab where students did a series of collisions and comparing the total momentum before and after the collision. It’s always tricky for students to make sense of the graphs produced by the photogates, so this year when we had some extra time the day before, I tried doing a few collisions and projecting the results. Then, I had students get into groups and whiteboard their interpretation of which velocity was which. That exercise paid off and the lab went the smoothest it ever has for me as students were much more confident at reading the graphs with the skill to back it up! We ended the week with Kelly O’Shea’s momentum card sort, and there was a really great moment where a student was explaining to me how he worked backwards to make a velocity vs. time graph from an equation by solving for the unknown velocity. Given how much I see students struggling with math reasoning, it was a lot of fun to see a student feeling confident enough to make sense of the equation in that way, which I don’t think would have happened if we’d gone straight to problems.

Days 77-81: Projectile Graphs & Cart Explosions

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AP Physics 1: Projectile Graphs

This week was all about velocity vs. time graphs for projectiles. We started with some video analysis of videos students had recorded to see what the graphs looked like. Students did a really nice job during the board meeting of connecting the graphs to other key ideas, like the forces acting on the projectiles. I showed students the three views of a projectile video from Pivot Interactives that shows a side view where the full 2D motion is visible, a top view where only the horizontal motion is visible, and a front view where only the vertical motion is visible. Even though we didn’t do an activity with the videos, students referred back to it when making sense of why we had two different velocity vs. time graphs. It was also fun to see more students making connections to derivatives now that they are further along in calculus than when we did motion in September.

Physics: Cart Explosions

Students did the cart explosion lab from the Modeling Instruction materials. They easily picked up on the pattern in the data, but I never feel like the connection between their data and the idea of conservation of momentum is as clear as I ‘d like. I think one trick is momentum doesn’t have a very good conceptual definition and mathematical reasoning has been challenging so far. Once we started working on momentum bar charts, students were doing really well with them and doing a lot of connecting the bar charts to what they’d observed in the lab, which was great!

Days 147-151: Free Fall Practicals & AP Review

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Physics: Projectile Practicals

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.

Days 142-146: Projectile Video Analysis & Angular Momentum

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Physics: Projectile Video Analysis

Students used Vernier Video Analysis to get velocity vs. time and position vs. time graphs for a projectile. I saw some students including their throw or after the projectile landed in their video analysis, which makes sense since I’ve seen students struggling more than in the past with recognizing what is the most relevant part of an object’s motion. I think that probably could have been addressed with spending a little more time on some pre-lab discussion. It was a lot of fun to hear their small-group discussions making sense of the graphs once I had them draw a free-body diagram and they recognized why the graphs looked the way they did.

AP Physics 1: Angular Momentum
We wrapped up unbalanced torque and rushed through angular momentum. Students started an activity in Pivot Interactives, but were moving through it more slowly than I’d hoped, so I ended up doing a lecture on angular momentum. It’s not my preferred approach, but the clock is ticking for AP exam day! Students seemed to get the concept during the lecture. I did a lot of emphasizing the parallels to linear momentum, which seemed to help. We’ll be doing some problems and whiteboarding next week to wrap up angular momentum, which will be a good opportunity for me to check how clear their understanding is.

Days 100-104: Momentum Conservation & Projectile Practical

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Physics: Momentum Conservation

This week we did a lot of work on conservation of momentum. We started with using photogates to measure the velocity of carts before and after a collision to reinforce the idea that momentum is transferred, then we did a momentum representations card sort from Kelly O’Shea before students tried some problems on their own. One thing I noticed is a lot of students are still struggling with what momentum is. I think a lot of students were having trouble taking in new ideas during distance learning, and are now struggling to build on those ideas. Students had a lot of great conversations during the card sort, and it was a lot of fun to see how they applied that thinking to the problems later in the week.

AP Physics 1: Projectile Practical

This week we wrapped up projectile motion. Students did a projectile practical where they predicted where a marble would hit the floor. I like to take advantage of the different masses of marbles I have and ask students to predict how the landing spot would change if they switched to a lighter marble, and students consistently nailed it. One fun thing has been seeing students use multiple different models to think about projectiles and the confidence I’m starting to see from more students.

Days 95-99: Cart Explosion Lab & Projectile Graphs

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Physics: Cart Explosion Lab

This week, we wrapped up the cart explosion lab and started working on momentum bar charts. My students had really good results on the cart explosion lab, but connecting it to momentum in the discussion is always rough. Students launch a spring-loaded cart and a standard cart off each other, figuring out where on a track to start them so they reach the ends at the same time, then record the ratio of the cart’s masses and the ratio of the distances they travelled before changing the mass and trying again. While I love that this low-tech approach incentivizes students to look for a pattern while they are collecting data, students struggle to connect the distances travelled to the velocities, I think mostly because there are so many different numbers flying around. During the discussion, my students had great results, but needed a lot of support to connect them to momentum. I want to rethink our momentum unit anyway, and I think part of that will include clarifying what I want students to get out of this lab and whether there are better ways to achieve that purpose.

AP Physics 1: Projectile Graphs

We started the week with a Pivot Interactives activity that shows three views of a projectile (full disclosure: I am an activity writer for Pivot Interactives). I’ve done video analysis, but I really like the way seeing the motion from different angles solidifies what I mean by the horizontal and vertical motion. It’s been a while since we did much with velocity vs. time graphs and students made solid connections to the forces acting on the projectile. We also worked through an activity I got from Michael Lerner where students describe the motion of an orange falling from a tower using every model we’ve learned so far, which really helped reinforce for students are aren’t really doing something new, just applying what we know to a new context.

Distance Learning Week 2

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AP Physics 1: Video Summative

Students started the week by wrapping up angular motion graphs. I took a page from Andy Rundquist and Rhett Allain by doing video assessments. I posted a goal-less problem, and each student had to record a short video explaining their work. I really enjoyed watching the videos, especially because a lot of students talked about things that almost tripped them up, but a lot of students had technical issues submitting their work. For the next assessment, I may give students the option of doing a video or a purely written version.

Physics: Projectile Motion Problems

Students worked some problems representing projectile motion, then did a video summative assessment. I tried designating part of my office hours specifically for discussing the problems, and I had a few students take me up on it. It was very different from talking in person, but the students who came felt like they got a lot out of it. Since I’m doing office hours anyway, that will be a pretty easy routine to continue.

Chemistry Essentials: Formula Writing

Students worked on translating between chemical formulas, names, and particle diagrams. Students learned how to go between names and formulas in the first half of the course, but a lot of my students took the first half trimester 1 and haven’t had chemistry since November, so it was worth some review. Plus, the particle diagrams are new to all of my students. Going by their work and the students I’ve had a chance to talk to, a lot of them needed this week, but have now gotten the hang of these representations.

The biggest issue was helping students figure out how to submit their work through Schoology. Many of them rarely visited Schoology before we switched to distance learning, so this is a lot to take in. I decided that I need to hold the line on getting students to submit assignments on Schoology rather than emailing their work to me to keep myself from getting overwhelmed. Fortunately, our digital learning coach has been putting together videos and other resources I can send along and the para supporting the course is willing to walk students through submitting their work.

Distance Learning Week 1

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After a three-week break, we started distance learning this week. Schoology had some outages and other issues from the increase in traffic that made things trickier. My district asked teachers to emphasize asynchronous instruction, which made the outages easier to work around. In spite of the challenges, it was good to connect with students again.

AP Physics 1: Circular Motion

My classes still need to do circular motion and rotation before the AP exam. I started this week with circular motion, emphasizing motion graphs. Since we’ve made a lot of use of linear motion graphs this year, students were quick to grasp the concepts and I think the relatively easy content helped students ease in to distance learning. Students collected data in Pivot Interactives, then posted their graphs to a discussion board for a virtual version of a “board meeting”. I didn’t have much interaction with my students since they didn’t have many questions, but, based on their work, they were able to get the concepts I was after and made sense of the graphs in the discussion board.

Physics: Projectile Motion Graphs

We usually start trimester 3 with projectile motion, and decided to stick with that plan since, like AP, working with velocity vs. time graphs let students ease in to distance learning with relatively familiar content. This also gave us the opportunity to have students collect their own data; they recorded their own videos of projectiles, then used Vernier Video Analysis to get the graphs. Like AP, they posted their graphs to a discussion board before answering some questions interpreting the graphs.

Students were consistently figuring out what I wanted them to, but struggled to feel confident in their answers, so I answered a lot of emails and had several video chats with students to work through questions. I also got some useful feedback from students. One commented that looking at the graphs on the discussion board wasn’t helpful because everyone’s graphs seemed really different, even though they all looked similar to me. I think some questions about the discussion board to steer students to key features would have been useful. In AP, I asked students to first post their graphs, then make a second post commenting on similarities and differences between their peer’s graphs, which I think would have been useful in this class, too.

A student also told me that she misses the collaboration and group work from our face-to-face class, because she found that extremely valuable for learning physics. Teachers in my building are holding office hours each week, and I am going to try designating a chunk of my office hours for student collaboration on a specific task. I’m also looking for ideas for asynchronous collaboration strategies, and would love to hear any!

Chemistry Essentials: Introductions

This is the course I’m the most worried about. It is the lowest (I hate that term) of our four levels of chemistry, so many of the students have not been well-served by our school. I find building relationships with students in this course is even more critical than in my physics courses. The trick is the start of the tri coincided with the start of distance learning, so I haven’t had the chance to meet any of my students face-to-face. I decided to make this week about connecting with students and helping them find their way around the course site. Their biggest assignment was to use the appointment slots in my Google Calendar to schedule an informal, one-on-one chat. I found it really valuable to hear about the things my students care about and to talk through their fears about distance learning. I’m hoping this will lower the threshold for them to come to office hours or make an appointment when they have a question about chemistry.

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

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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

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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