# Day 30: Center of Mass, Whiteboarding, & Energy Bar Charts

AP Physics 1: Center of Mass

Students worked on a video analysis of two air pucks attached by a rod from the article by Taylor Kaar, Linda Pollack, Michael Lerner, and Robert Engles in The Physics Teacher. In the past, I’ve used LoggerPro, but there have been delays on getting it installed on student computers, so I took advantage of the video upload feature in Pivot Interactives. Pivot has a ruler with an adjustable length to get measurements to scale, but it was tricky to find a nice alignment, so students ended up skipping scaling the ruler and coming up with a conversion factor, instead.

Physics: Whiteboarding

Students whiteboarded some problems on drawing free body diagrams. In my 1st hour, we did mistakes whiteboarding; I was a little disappointed that no groups put a forward force on the objects moving forward, but not a lot of students made that mistake while they were working on the problems in the first place. My 6th hour is a little behind, so they mostly worked on the problems today and will do some abbreviated whiteboarding tomorrow.

Chemistry Essentials: Energy Bar Charts

Students worked on some LOL diagrams for energy transformations during phase changes. They had some trouble with the system flow part of the diagram, mostly because they are getting tripped up by the idea that it needs to list specific objects.

# Day 29: Collisions, Card Sort Part 2, & Board Meeting

AP Physics 1: Collisions

Students started working on a lab to compare the momentum before and after a collision between two carts. This was their first time using photogates, so the first data point took some time, but then students were able to get data pretty quickly. One student pointed out I’d posted “spoiler alert” instead of a learning target, so we took a few minutes to talk about why I don’t always want to post a learning target at the beginning of a new lab.

Physics: Cart Sort Part 2

We did some whiteboarding Kelly O’Shea’s balanced forces card sort. Students seem to be doing well with what each representation shows. Students are having some trouble with the direction of the normal force, so I took some inspiration from Joe Cossette and did a quick demo where I put a balance on a board, then slowly lifted one end.

Chemistry Essentials: Board Meeting

We whiteboarded the results of last week’s lauric acid phase change lab. Students pretty readily recognized the flat sections of their graphs that occurred during a phase change. I haven’t spent a lot of time setting up the concept of energy in this class, so I think they had some trouble with the idea that the water baths were still changing the energy of the lauric acid when the temperature wasn’t changing, but I think we’ll get there.

# Day 28: Assessment, Card Sort, & Phase Changes

AP Physics 1: Assessment

Students to a quiz on free-body diagrams and momentum, which ended up taking a much bigger chunk of the hour than I’d hoped. In one of my classes, students are starting to ask for reading strategies for deciphering problems, which is great. I tend to get a lot of students who are very strong readers, so I usually wait until there is a problem on an assessment that a lot of students clearly got wrong because of reading to ensure students see a need for reading strategies, but since my students are self-aware enough to realize they could use some new strategies before its an issue, I’m happy to start in on those strategies early.

Physics: Card Sort

Students did a balanced forces card sort from Kelly O’Shea, with a lot of influence from Richard Wright, though I left out the system schema that Michael Lerner added. Before the card sort, I spent some time talking about system schema and free-body diagrams, but left my students to figure out the vector addition diagrams in the card sort. In my 1st hour, this went really well; there were great conversations, and my students seem to really get vector addition diagrams. In my 6th hour, things were much rougher; they tend to be less focused (its like they’ve had five classes before mine or something) and I could tell they hadn’t gotten as much out of yesterday’s interaction stations, which made it very tough to build on today. In general, I think I need to do a better job of adjusting to my 6th hour.

Chemistry Essentials: Phase Changes

Students collected temperature and time data for lauric acid as it went from solid to liquid and back again. The data collection requires constant stirring and recording the temperature every 20 seconds, but the graph comes out really nice.

# Day 27: Problems, Interaction Stations, & States of Matter

AP Physics 1: Problems

It was a little tricky figuring out what I could leave for students to work on. I ended up giving them some additional problems on impulse and quantitative force diagrams. I ended up giving them their first taste of a goal-less problem and I’m looking forward to seeing what they do.

Physics: Interaction Stations

I usually avoid leaving anything equipment intensive when I have a sub, but we had Brian Frank’s interaction stations on deck for today. The other physics teacher and I try to stay within a day or so of each other, so we set the stations up in his room, then his classes and mine will switch places the hours I have physics.

Chemistry Essentials: States of Matter

Plan A was for my co-teacher to introduce phase changes by having students do a lab making a temperature vs. time graph for lauric acid as it melts and re-freezes. Then, on Tuesday, we found out a fire drill was scheduled for the start of this hour. Since a lot of students in the class really struggle with transitions and with changes to the routine, a sub, plus a fire drill, plus a lab just seemed like a disaster. I ended up putting together a reading assignment from the textbook introducing the three states of matter we’ll be working with.

# Day 86: Standing Waves, Energy Conservation, & Quiz

I was home sick, so no photos today.

AP Physics: Standing Waves

Students worked on a lab in Pivot Interactives to find a relationship between frequency and the wavelength of a standing wave.

Physics: Energy Conservation

Students worked on some problems using energy conservation. I’ve had some issues with students not attempting problems when there is a sub, so I spent some time yesterday on strategies for making progress on energy problems.

Chemistry Essentials: Quiz

Students too their quiz on energy and phase change.

# Day 85: Whiteboards Galore

AP Physics: SHM Whiteboarding

Students did some whiteboarding to discuss yesterday’s trio of simple harmonic motion. There was some good discussion about whether the net force on each object is constant or changing for each object. In one section, I asked students for free-body diagrams and vector-addition diagrams to resolve that debate and in the other section, I asked them to sketch velocity vs. time graphs. The velocity vs. time graphs were much more effective for resolving the disagreement.

Physics: Kinetic Energy Board Meeting

Students whiteboarded their results for the kinetic energy lab. This time, I didn’t specifically prompt them to linearize their graphs and only some groups tried plotting change in height vs. velocity squared, which made for a nice discussion.

Chemistry Essentials: Freezing Lauric Acid

Students finished making their graphs, then we discussed the results of the lauric acid lab. A lot of students had trouble with a question about whether you can add energy to a system without changing the temperature, which reinforces my impression that many of those students are having trouble making sense of what the representations we’re using mean. I also forgot I wanted to have my students move before we shifted to whole group discussion and didn’t think of it until after class. Enough groups had trouble shifting to whole class mode that I need to make a note for next time.

# Day 84: SHM Trio, Kinetic Energy, & Lauric Acid Take 2

Yesterday was a snow day.

AP Physics: SHM Trio

Students analyzed a video from Pivot Interactives of a pendulum, a spring, and a rotating disk in synchronized simple harmonic motion. I overheard some really good conversations about differences between the x-position vs. time and y-position vs. time graphs for the pendulum; a few students relate it back to the projectile Pivot Interactive we’d done and tried to imagine a camera that just showed the vertical motion of the pendulum.

Physics: Kinetic Energy

Students started collecting data to find a relationship between the change in height of a cart on a ramp and the velocity at the bottom. On the elastic potential energy lab, a lot of students just measured the height of the cart, rather than the change in height, so I spent some extra time on the pre-lab discussion to make sure students saw why the change is important.

Chemistry Essentials: Lauric Acid Take 2

We took another shot at finding the freezing point of lauric acid since the weather on Monday cut us short. A few students who’d collected some data were frustrated that they had to start fresh, rather than picking up where they left off. It will probably be worth spending some time tomorrow on why they had to start fresh, especially since it connects to what the graph physically means.

# Day 83: Inertial vs. Gravitational Mass, Board Meeting, & Freezing Lauric Acid

Several nearby districts had snow days today, so most of my classes were a little more off-task than usual today.

AP Physics: Inertial vs. Gravitational Mass

Students finished collecting data and making graphs for the period of a spring lab. We didn’t have enough time for a board meeting, but every group had decided mass is what matters so we took a few minutes to decide whether it is gravitational or inertial mass by comparing the period of a cart on a spring at different angles. This is the first year I’ve used the Pasco equal length springs, and several groups were able to get some pretty nice data for period and spring constant.

Physics: Board Meeting

Students whiteboarded their results from last week’s lab. I gave different groups different springs, and the slopes reflected that variation nicely which lead smoothly into fitting k into the formula. I had conversations with some groups about whether their results were “right” that reinforced just how uncomfortable some of my students still are with being even partially wrong. Talking to them, I think they don’t see this fear of being wrong as an obstacle to learning physics.

Chemistry Essentials: Freezing Lauric Acid

We worked on a lab to find the freezing point of lauric acid by melting it in a hot water bath, then making a temperature vs. time graph as it cools in a cool water bath. This is the last class of the day and we ended up getting released 13 minutes early due to a snowstorm, so only one group was able to get data. Especially since a third of the class was gone by 6th hour, I’m thinking about just repeating the lab tomorrow.

# Day 82: Springs, Linearization, & Whiteboarding

AP Physics: Springs

Students started collecting data for variables that affect the period of a spring. I found it interesting that students were quick to suggest stretching the spring farther to change the period after seeing angle doesn’t matter for a pendulum; I suspect they just aren’t making the connection yet. A lot of groups used motion detectors to measure the period, and one student found the graphs so satisfying she snapped a photo of the LabQuest to show off.

Physics: Linearization

Students were pretty quick to treat yesterday’s data on the compression of a spring launcher vs. a cart’s change in height as linear, probably because we haven’t linearized any graphs in a while. We spent some time today talking about what intercept would make sense and why before a quick review of linearization. Afterwards, groups worked on making linearized graphs of their data.

Chemistry Essentials: Whiteboarding

Students did some whiteboarding the problems from yesterday. I had all groups whiteboard the same problem, when we shifted to whole group discussion. The physical space in my room lends itself pretty well to having whole group discussions with students at the lab tables, but a lot of students were having trouble with the transition to whole group discussion. Next time, I think I will have students physically move to give a clearer cue that we are changing the kind of activity.

# Day 81: Board Meeting, Energy Transfer, & LOL Diagrams

AP Physics: Board Meeting

Students whiteboarded the graphs for the pendulum lab. It usually feels a little hand-wavy getting from the lines of best fit to the full equation; I had one group a couple of years ago that reasoned out gravity should be involved, and connected the dots from there. I’d like to work on scaffolding strategies next time to give students the opportunity to take those steps themselves.

Physics: Energy Transfer

We revisited the previous energy transfer lab to come up with a formula for gravitational potential energy, then started a lab to find a relationship between the compression of a spring and the amount of gravitational potential energy transferred to a cart. Students were pretty quick to accept a linear fit to their data, so I want to make sure we spend some time tomorrow on the intercept of the graph.

Chemistry Essentials: LOL Diagrams

I introduced students to LOL diagrams and they used them to represent some phase change problems. Students took to the diagrams pretty easily, which was great to see.