# Days 92-96: Springs & Impulse

On Friday last week, I found out our new physics teacher would be starting this week. I went into this year expecting to be doing my role as science content specialist full-time and it has been tricky to juggle that work with my teaching. I’m excited to be able to focus more on my role, but it is hard to be getting ready to leave students I’ve been with for a while. The new teacher shadowed me this week so he could start getting to know the students and the curriculum. We will then be co-teaching until the trimester ends on March 10. Trimester 3, he will take over Physics completely. I’ll still be in AP Physics 1 on occasion up through the AP exam since this is our new teacher’s first time doing AP and it’s a lot to get the hang of in a short amount of time!

AP Physics: Springs

Students conducted an experiment to find factors that affect the period of a spring. The data was kind of rough, mostly because they were having trouble getting the springs to oscillate nicely. We still had enough good data in the class that we were able to figure out all the things we needed to. On both this and the pendulum lab, I was really pleased with how students used the intercept of their graph to figure out they needed to linearize. After the lab, we worked on some problems with representations for simple harmonic motion. It was a lot of fun to see students putting together forces, energy, and motion graphs to make sense of simple harmonic motion and they made a lot of great connections.

Physics: Impulse

This year, we tried a new sequence for momentum where we started with conservation of momentum since looking at a system that includes both objects in a collision is a really strong motivator to learn momentum. This week, we did Newton’s 3rd Law and used that combined with Newton’s 2nd Law to derive impulse and start thinking about individual objects. This was a tough transition for a lot of students to make and I’m wondering about ways we could make it smoother in the future. One thought is we don’t emphasize system choice in Physics, but that is pretty key to thinking about impulse. I’m not sure what to do with this thought yet, but definetly want to keep it in mind.

# Days 41-45: Conservation of Momentum & Newton’s 3rd Law

This week we developed conservation of momentum. Previously, I started with impulse and momentum of single objects, then built up to conservation in systems. I’ve never been thrilled with my storyline, so this year I am trying putting conservation of momentum first, then we will work toward impulse. Once we’d done a lab with some collisions and talked about momentum bar charts, we did Kelly O’Shea’s multiple representations of momentum card sort to incorporate mathematical representations. The card sort really helped my students feel confident with the bar charts and to make sense of the mathematical representations.

We ended the week with Newton’s 3rd Law. I feel like this law fits better with my momentum storyline than my forces one, so this was their first introduction to the 3rd Law. I had students predict how the forces would compare on two carts for a variety of collisions, then we actually tested the collisions out using some force sensors with hoop springs. This is a very rare time that I ask students to make a prediction that I think they are likely to have wrong, so was very intentional in talking to students about my goal of pulling out their existing ideas so we could contrast with the accepted physics. I also made sure we talked about what useful thinking lead them to the incorrect predictions and what physics their predictions showed they know. There was a fantastic moment partway through where a student articulated that both the forces we were measuring came from the same interaction, so it made sense for the size of the force to be the same. She also realized the cart she expected to experience a bigger force did have a bigger change in motion, which was a great opportunity to validate the thinking that lead to that prediction. It was a great note to end the week on.

# Days 68-72: Energy Practical & Pushing Boxes

AP Physics 1: Energy Practical

This week, students worked on applying conservation of energy. We wrapped it up with a lab practical to find the spring constant of a popper toy. To help with what makes a good procedure, I had groups start by writing out the steps they were going to follow on a whiteboard. Then, they traded whiteboards with another group and had to follow the procedure they were given to actually collect data. One group came up with a nice strategy of writing out the equation they’d use in their calculations, then checking off each variable as they added a step to measure it.

Physics: Pushing Boxes

Students spent a lot of time this week on problems applying Newton’s 3rd Law and synthesizing Newton’s Laws, including some great problems originally from Matt Greenwolfe where students draw free-body diagrams and velocity vs. time graphs for boxes pushed across various floors. While there was some great discussion, I think these problems would have been more valuable much earlier in the forces model. In general, I think Newton’s 3rd Law feels like an afterthought in how we approach forces. With some shifts in what we’re doing early in this model, we could better integrate key elements of this model and reduce the need for doing some kind of synthesis at this point in the unit.

# Days 63-67: LOL Diagrams & Newton’s 3rd Law

AP Physics 1: LOL Diagrams

Students worked on sketching bar charts and LOL diagrams to show energy transfers. I was really pleased with how comfortable students were switching between different systems. I started out the week by having students use a spring scale to pull a cart up different ramps, always raising their cart to the same height above the table. We then sketched force vs. displacement graphs to introduce the idea of work and gravitational potential energy. Getting both simultaneously meant the concepts blurred together for students at first, but that issue got resolved as we did mistakes whiteboarding with energy bar charts and LOL diagrams.

Physics: Newton’s 3rd Law

One of our major tasks this week was developing Newton’s 3rd Law. Students started by predicting how the forces on two colliding carts would compare, then we tested out the collisions. As we tested the collisions, I cued students to notice the relative accelerations of the carts, which I think helped students see the useful thinking in their original predictions. Before we officially stated Newton’s 3rd Law, I borrowed an idea from Mark Schober and had students play with film canisters with magnets inside to test and refine their rule before the whole-class discussion.

# Days 32-35: Newton’s 3rd Law & Newton’s 1st Law

This was another short week. Parent-teacher conferences were on Thursday night, so Friday was scheduled as a professional development day.

AP Physics 1: Newton’s 3rd Law

This week our focus was on Newton’s 3rd Law. Students predicted which cart would experience a larger force during various collisions, which we then tested using a pair of carts with force sensors and hoop springs. In my grad class this semester, we’ve been doing a lot of talking about the ways language students use can mask meaningful understanding, which got me thinking about how I can make better use of students’ predictions. This year, I tried being very explicit that our task was to find the useful ideas in students’ predictions and to translate those useful ideas into the language physicists use. There was a great moment where a student said “So the force and the result of the force are different things, but we were treating them as the same”, which I couldn’t have planned better.

I also took a page from Brian Frank this week and used some magnetic hooks for an easy setup of a static forces lab practical.

Physics: Newton’s 1st Law

This week was about developing the idea of a force and Newton’s 1st Law using interaction stations and the bowling ball lab. A few students were resistant to actually trying the bowling ball lab this year, rather than actually testing whether what they expected worked, so I had to push some groups to really explore getting the bowling ball moving with a constant speed. Once they got started, however, there was some great discussion.

# Day 53: Day Before Break

Today was the last day to submit work or complete retakes before the end of the term and our last day of classes before Thanksgiving break, so it was a very chaotic day.

AP Physics 1: Whiteboarding

Students wrapped up presenting the whiteboards from yesterday. There was some really great discussion, with students making use of the matter model and connecting to the collisions we’d tested out a few days ago.

Physics: Whiteboarding

This class also worked on wrapping up whiteboarding some problems. My 6th hour had a really tough time focusing, which was not surprising the last hour of the day before a break. While we still got where we needed to, I don’t think a whiteboard discussion of problems was the right call for today.

Chemistry Essentials: Quiz

Students took their quiz on naming and formula writing for ionic and covalent bonds. Since it was fairly short, we spent some time before the quiz whiteboarding a few practice problems. A few students were focused on last-ditch efforts to raise their grade, and it was tough to re-direct them to the day’s activities. This will be something to think about at the end of next trimester.

# Day 52: Mistakes Whiteboarding &Binary Compounds

AP Physics 1: Mistakes Whiteboarding

We started looking at some force problems involving Newton’s 3rd Law by doing some mistakes whiteboarding. There was a lot of good discussion on the directions of normal forces in problems where the normal doesn’t just go straight up.

Physics: Mistakes Whiteboarding

This class also did mistakes whiteboarding, even with the same problems as in AP. Once again, there was a lot of good discussion on the direction of the normal forces.

Chemistry Essentials: Binary Compounds

Students practiced translating between names and formulas for binary compounds. Most students took to this pretty quickly and easily, which was great to see.

# Day 51: Problems, 3rd Law, & Covalent Bonds

AP Physics 1: Problems

Students worked some problems on balanced forces, with an emphasis on Newton’s 3rd Law. We also started talking a little bit about the final exam, which will be a modified practice AP exam.

Physics: 3rd Law

Students predicted how the forces would compare during a series of collisions, then we tested teach collision out using a a pair of force sensors with hoop springs attached. Partway through the testing, a few students made the connection to Newton’s 3rd Law, which was fun to see.

Chemistry Essentials: Covalent Bonds

I introduced students to covalent bonding today. We aren’t going into much depth on figuring out the formulas, but we did take some time today to sketch electron diagrams (simplified Lewis dot structures) to get at what is going on during a covalent bond.

# Day 49: Newton’s 3rd Law, Whiteboarding, & Polyatomic Ions

AP Physics 1: Newton’s 3rd Law

Students predicted the relative forces on two carts in various collisions, then we tested them using a pair of carts with force sensors. I really like using hoop springs for this since it gives a very clear visual in addition to the force vs. time graphs.

Physics: Whiteboarding

Students whiteboarded the problems they worked on yesterday for a gallery walk. We set up the packet to re-use the problems we had that just deal with representations.

After discussing the problems, I showed students a video I’d recorded on our elevator and asked them to write a CER for whether I took the elevator up or down.

Chemistry Essentials: Polyatomic Ions

We added polyatomic ions to the formula writing we’ve been doing. Students seem to be getting the hang of how to figure out the formula. Some students have figured out the “flop and drop” strategy, and others are opting to draw the simplified Lewis dot structures we’ve been using when they get stuck.

# Day 153: Levitating Globe, Pinhole Viewers, & Hollow Pennies

AP Physics: Levitating Globe

The approach I’ve fallen into in order to give students time for their final projects while embedding some review for the students who will be taking the AP Physics 1 exam on the make-up date. Today, I got out a globe that floats in a magnetic stand and asked students to predict what should happen to the reading on a balance when the globe is removed, an idea I got from Kelly O’Shea. One group did a thought experiment where the magnet was replaced with a spring supporting the globe to reason their answer and had a great conversation.

Physics: Pinhole Viewers

We discussed some of the results of yesterday’s lab, focusing on how a ray diagram can explain the observations students made. Students are pretty quickly getting then hang of making sense of these diagrams.

Chemistry Essentials: Hollow Pennies

Students did a conceptual lab practical on activity series today. I gave students an activity series for metals, then asked them to predict whether copper or zinc is more likely to react with hydrochloric acid. Then, I gave each student a penny with a wedge filed into it to test their prediction. I also showed students the hollow remnants of a penny that had been left in 12M hydrochloric acid for a few hours.